How to speed up full text query on a table with 4 million rows? (MariaDB)
How big is the dataset?  SHOW TABLE STATUS.

It sounds like it is much less than innodb_buffer_pool_size, so it will probably reside in RAM once it is loaded.

There is no automatic way to get it loaded.  You could write a script to access every row in the data and every index.  But that is tricky and slow.

On the other hand, you can keep it loaded (at least across graceful shutdowns) by turning ON these:  innodb_buffer_pool_dump_at_shutdown and innodb_buffer_pool_load_at_shutdown.