VoltDB has a variety of client libraries available (java and JDBC is included, others are at http://voltdb.com/dev-center/libraries-and-tools/), so chances are there is a library that could work with your application.
VoltDB includes an "Export" feature that integrates with other databases using JDBC. Records can be committed in VoltDB to in-memory export tables, and then VoltDB will hand off efficient batches to a downstream database. The export process will ensure records are committed downstream before removing them from the export table. You can read more about the Export feature in Using VoltDB, Chapter 13. Exporting Live Data.
It is up to you when to insert records into an export table. It could be done in a series of transactions lazily running in the background of your application to collect and delete data that has aged more than 365 days. You might also export data as it is ingested, so that MySQL can hold essentially all of the data almost immediately, but doesn't have to stand up to the firehose of incoming requests. Data could then be retained in VoltDB for whatever duration your application requires and then deleted (rather than exported) as it ages.