https://dev.mysql.com/doc/refman/5.5/en/events-metadata.html
For representation of event information in the mysql.event table, the execute_at, starts, and ends times are converted to UTC and stored along with the event time zone. This enables event execution to proceed as defined regardless of any subsequent changes to the server time zone or daylight saving time effects. The last_executed time is also stored in UTC.
If you select information from mysql.event, the times just mentioned are retrieved as UTC values. These times can also be obtained by selecting from the INFORMATION_SCHEMA.EVENTS table or from SHOW EVENTS, but they are reported as ETZ values. Other times available from these sources indicate when an event was created or last altered; these are displayed as STZ values. The following table summarizes representation of event times.
Value mysql.event INFORMATION_SCHEMA.EVENTS SHOW EVENTS
Execute at UTC ETZ ETZ
Starts UTC ETZ ETZ
Ends UTC ETZ ETZ
Last executed UTC ETZ n/a
Created STZ STZ n/a
Last altered STZ STZ n/a