Hi,
As per your explain plan of those queries, it looks like your queries are using proper indexes. Still if you want to check where exactly it’s taking time, I would suggest to use profiling. Please check below links for how to use it.
[URL]http://dev.mysql.com/doc/refman/5.5/en/show-profile.html[/URL]
[URL]http://www.mysqlperformanceblog.com/2012/02/20/how-to-convert-show-profiles-into-a-real-profile/[/URL]