What ongoing maintenance is needed for a MySQL environment?
It just works!

Seriously though, if you got a master with two replicas environment, you probably want to do occasional consistency checks with pt-table-checksum. Replication does not guarantee consistency (and writes can happen on replicas too).

Otherwise:


Verify your backups to make sure you can actually recover (most of our data recovery customers thought they have backups, but they were actually not working).
Query reviews - definitely worth learning how to do that so you can review them proactively.
Do check error logs - any corruption errors will show up there.


There are many other things you can do, but I try to live by the rule: don't fix what ain't broken.

Good luck!