MySQL Problem

I use WP 3.51 for my site and am having problems with my webhost throttling my account because of slow mysql queries. Below is one such query. I used * to blot out some numbers and my database bame since I’m not sure how much I should include and what I shouldn’t.

You’ll see the query was really slow. It was 32 seconds and they say throttling happens to any account that has a sql query over 1 second. Can anyone tell me what could be causing this? Easy answer is “a plugin” but can anyone with expertise guide me to what kind of plugin or if it could be something else?

Here is one of my recent slow queries. I’ve had others that look at 4000 rows, but this one only looked at 6. But the query took 32x longer than what my web host allows before throttling my account.

Thanks for any help you can provide,
Brian

RECENT SLOW QUERY
# Tue MAR 26 05:22:39 2013
# Query_time: 32.903254 Lock_time: 0.000836 Rows_sent: 3 Rows_examined: 6
use the*****_wrd335;
SET timestamp=13***59;
SELECT wp_comments.* FROM wp_comments JOIN wp_posts ON ( wp_comments.comment_post_ID = wp_posts.ID ) WHERE post_status = ‘publish’ AND comment_approved = ‘1’ ORDER BY comment_date_gmt DESC LIMIT 3