Долгие запросы MySql

SELECT i.*, r.score AS is_rated, u.nickname AS user_nickname, u.avatar AS user_avatar
FROM cms_comments i
JOIN (SELECT id FROM cms_comments WHERE is_deleted IS NULL ORDER BY id DESC LIMIT 961880, 20 ) c ON c.id = i.id LEFT JOIN cms_users AS u ON u.id = i.user_id
LEFT JOIN cms_comments_rating AS r ON r.comment_id = i.id AND r.user_id='86'
WHERE (i.is_deleted IS NULL) AND (i.is_approved = '1')
ORDER BY i.date_pub DESC
LIMIT 20
Время выполнения 1.07298 секунд

# TIME: 180306 11:28:25
# USER@Host: ******** @ localhost []
# Thread_id: 115670  Schema: *****  QC_hit: No
# Query_time: 31.944684  Lock_time: 0.000539  Rows_sent: 20  Rows_examined: 1853053
SET TIMESTAMP=1520324905;
SELECT   i.*, r.score AS is_rated, u.nickname AS user_nickname, u.avatar AS user_avatar
                FROM cms_comments i
                LEFT JOIN cms_users AS u ON u.id = i.user_id
LEFT JOIN cms_comments_rating AS r ON r.comment_id = i.id AND r.user_id='0'
WHERE (i.is_private = '0')  AND  (i.is_deleted IS NULL)  AND  (i.is_approved = '1')
ORDER BY i.date_pub DESC
LIMIT 926580, 20;