Login to phpMyAdmin, highlight your database and browse the tables. Check the “Type” column to see what type of tables they are…
Use phpMyAdmin SQL tab and run the query to find the tables that might still be MyISAM:
SELECT TABLE_NAME, ENGINE FROM information_schema.TABLES WHERE TABLE_SCHEMA = 'yourdatabasename' and ENGINE = 'MyISAM';
Depending on when you installed WordPress and what’s transpired since then, it could be that some, or all, of your database tables are still MyISAM. While this is perfectly acceptable - many sites have run MyISAM for ages, there are some reasons to consider moving over to InnoDB.
InnoDB is a generational step forward from MyISAM, providing features like transaction handling, foreign key constraints (so that it’s a relational database) and row level locking. Performance benchmarks show InnoDB to be the favorite as well.