Option 1:
Login to phpMyAdmin, highlight your database and browse the tables. Check the “Type” column to see what type of tables they are…
Option 2:
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.