mysql order by/group by 优化

explain select im.item_id from property_value p left join item i on p.id = i.value left join
item_message im on i.item_id = im.item_id where ( p.value like '%餐饮%' or p.value like '%拉%' )  and im.class = 1 and im.status = 0 and p.`property_id` in (SELECT id from
`property` WHERE `key_p` = 1) LIMIT 24 , 8


id  select_type  table  type  possible_keys  key  key_len  ref  rows  Extra 
1 PRIMARY im ref class,item_id class 4 const 9096 Using where
1 PRIMARY i ref value,item_id item_id 4 fenlei.im.item_id 8 Using where
1 PRIMARY p eq_ref PRIMARY PRIMARY 4 fenlei.i.value 1 Using where
2 DEPENDENT SUBQUERY property unique_subquery PRIMARY PRIMARY 4 func 1 Using where


explain select count(im.item_id), im.item_id from property_value p left join item i on p.id = i.value left join
item_message im on i.item_id = im.item_id where ( p.value like '%餐饮%' or p.value like '%拉%' )  and im.class = 1 and im.status = 0 and p.`property_id` in (SELECT id from
`property` WHERE `key_p` = 1) group by im.item_id LIMIT 20 , 8

id  select_type  table  type  possible_keys  key  key_len  ref  rows  Extra 
1 PRIMARY im index class,item_id item_id 4 NULL 3 Using where
1 PRIMARY i ref value,item_id item_id 4 fenlei.im.item_id 8 Us