So you know how to add indexes to speed queries and maybe can use EXPLAIN. But why do your queries still stink? This session covers how the MySQL Optimizer looks at your SQL statements, where it has to throw up its hands in frustration, and how to tame it. Plus, there are some minor data architecture tweaks you need to know.
Slides at https://www.slideshare.net/davidmstokes/advanced-mysql-query-optimizations but the demos are only in the presentation.