Temporary table creation takes long time RDS Server

Question

Below query takes long time to create temporary table, its only have "228000" distinct record.

DECLARE todate,fromdate DATETIME;

SET fromdate=DATE_SUB(UTC_TIMESTAMP(),INTERVAL 2 DAY);
SET todate=DATE_ADD(UTC_TIMESTAMP(),INTERVAL 14 DAY);


SET SESSION TRANSACTION ISOLATION LEVEL READ COMMITTED;

 DROP TEMPORARY TABLE IF EXISTS tempabc;


SET max_heap_table_size = 1024*1024*1024;

CREATE TEMPORARY TABLE IF NOT EXISTS tempabc
-- (index using BTREE(id))
ENGINE=MEMORY

AS
( 
    SELECT SQL_NO_CACHE DISTINCT id
    FROM abc 
    WHERE StartTime BETWEEN fromdate AND todate
);

I already created index on 'startTime' coulmn, still it tooks 20 sec to create table. Kindly help me out to reduce the creation time.

More Info:-

I changed my query earlier I was using "tempabc" temporary table to get my output, now I am using IN clause instead of temporary table and now it is taking 12 sec to execute, but still more than expected time..

Earlier(taking 20-30 sec)

 DECLARE todate,fromdate DATETIME;

    SET fromdate=DATE_SUB(UTC_TIMESTAMP(),INTERVAL 2 DAY);
    SET todate=DATE_ADD(UTC_TIMESTAMP(),INTERVAL 14 DAY);


    SET SESSION TRANSACTION ISOLATION LEVEL READ COMMITTED;

     DROP TEMPORARY TABLE IF EXISTS tempabc;


    SET max_heap_table_size = 1024*1024*1024;

    CREATE TEMPORARY TABLE IF NOT EXISTS tempabc
    -- (index using BTREE(id))
    ENGINE=MEMORY

    AS
    ( 
        SELECT SQL_NO_CACHE DISTINCT id
        FROM abc 
        WHERE StartTime BETWEEN fromdate AND todate
    );

SELECT DISTINCT p.xyzID
                FROM tempabc s
                JOIN xyz_tab p ON p.xyzID=s.ID AND IFNULL(IsGeneric,0)=0;

Now(taking 12-14 sec)

 DECLARE todate,fromdate Timestamp;

    SET fromdate=DATE_SUB(UTC_TIMESTAMP(),INTERVAL 2 DAY);
    SET todate=DATE_ADD(UTC_TIMESTAMP(),INTERVAL 14 DAY);

    SELECT   p.xyzID FROM xyz_tab p
        WHERE id IN (
             SELECT DISTINCT id FROM abc 
                 WHERE StartTime BETWEEN fromdate AND todate )
          AND  IFNULL(IsGeneric,0)=0 GROUP BY p.xyxID;

But we need to achieve 3-5 sec of execution time.

This is my explain output.

*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: abc
   partitions: NULL
         type: index
possible_keys: ix_starttime_id,IDX_Start_time,IX_id_starttime,IX_id_starttime_prgsvcid
          key: IX_id_starttime
      key_len: 163
          ref: NULL
         rows: 18779876
     filtered: 1.27
        Extra: Using where; Using index; Using temporary; Using filesort; LooseScan
*************************** 2. row ***************************
           id: 1
  select_type: SIMPLE
        table: p
   partitions: NULL
         type: eq_ref
possible_keys: PRIMARY,IX_seriesid
          key: PRIMARY
      key_len: 152
          ref: onconnectdb.abc.ID
         rows: 1
     filtered: 100.00
        Extra: Using where

Explain in JSON format

EXPLAIN: {
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "10139148.44"
    },
    "grouping_operation": {
      "using_temporary_table": true,
      "using_filesort": true,
      "cost_info": {
        "sort_cost": "1.00"
      },
      "nested_loop": [
        {
          "table": {
            "table_name": "abc",
            "access_type": "index",
            "possible_keys": [
              "ix_starttime_tmsid",
              "IDX_Start_time",
              "IX_id_starttime",
              "IX_id_starttime_prgsvcid"
            ],
            "key": "IX_id_starttime",
            "used_key_parts": [
              "ID",
              "StartTime",
              "EndTime"
            ],
            "key_length": "163",
            "rows_examined_per_scan": 19280092,
            "rows_produced_per_join": 264059,
            "filtered": "1.37",
            "using_index": true,
            "loosescan": true,
            "cost_info": {
              "read_cost": "393472.45",
              "eval_cost": "52812.00",
              "prefix_cost": "446284.45",
              "data_read_per_join": "2G"
            },
            "used_columns": [
              "ID",
              "StartTime"
            ],
            "attached_condition": "(`onconnectdb`.`abc`.`StartTime` between <cache>(fromdate@1) and <cache>(todate@0))"
          }
        },
        {
          "table": {
            "table_name": "p",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY",
              "IX_seriesid"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "ID"
            ],
            "key_length": "152",
            "ref": [
              "onconnectdb.abc.ID"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 1,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "9640051.00",
              "eval_cost": "0.20",
              "prefix_cost": "10139147.44",
              "data_read_per_join": "2K"
            },
            "used_columns": [
              "ID",
              "xyzID",
              "IsGeneric"
            ],
            "attached_condition": "(ifnull(`onconnectdb`.`p`.`IsGeneric`,0) = 0)"
          }
        }
      ]
    }
  }
}

Please suggest.