Last access of a DB in Mysql



I have “inherited” a collection of Mysql DBs (~900) and I would like to know which of them are actually being used. I looked around and I can find some commands like:

SELECT from_unixtime(UNIX_TIMESTAMP(MAX(UPDATE_TIME))) as last_update FROM information_schema.tables WHERE TABLE_SCHEMA='MY_DB' GROUP BY TABLE_SCHEMA;

but this does not really tell me if MY_DB is being accessed by some web service or users, right? It only informs about when it was last updated, unless I got it wrong. If so, is there a more accurate way to find out the last access of a DB?

Thank you!