I have a query that is taking around 7 seconds. I break it into two queries which provides the same data as the first, and it takes around 0.01 seconds. I had thought that I properly indexed it, however, likely had not. The database currently has very little data in it. I am using MySQL 5.5.46. I am using PHP with PDO, however, I don't think that is relevant, and purposely did not tag this question with PHP or PDO.

I am not asking why my specific query is taking so long or how to identify slow queries, but am asking for the generic steps to determine the cause of a slow query. I expect that `EXPLAIN` will be used. What are you looking for in `EXPLAIN`? What other steps could one take?