mysql> describe SELECT COUNT( m.id )
-> FROM mos_content AS i
-> LEFT JOIN mos_sections AS s ON i.sectionid=s.id
-> LEFT JOIN mos_menu AS m ON m.componentid=s.id
-> WHERE m.type='content_blog_section'
-> AND m.published='1';
+----+-------------+-------+-------+-----------------------------------------+-------------+---------+--------------------------+-------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+-------+-----------------------------------------+-------------+---------+--------------------------+-------+-------------+
| 1 | SIMPLE | i | index | NULL | idx_section | 4 | NULL | 21461 | Using index |
| 1 | SIMPLE | s | ref | PRIMARY,lento2 | lento2 | 4 | notitrujillo.i.sectionid | 1 | Using index |
| 1 | SIMPLE | m | ref | componentid,lento2,lento3,lento4,lento6 | componentid | 4 | notitrujillo.s.id | 3 | Using where |
+----+-------------+-------+-------+-----------------------------------------+-------------+---------+--------------------------+-------+-------------+