SELECT 
  cscart_discussion.object_id AS product_id, 
  AVG(
    cscart_discussion_rating.rating_value
  ) AS average_rating, 
  cscart_discussion.type AS discussion_type, 
  cscart_discussion.thread_id AS discussion_thread_id 
FROM 
  cscart_discussion 
  LEFT JOIN cscart_discussion_posts ON cscart_discussion_posts.thread_id = cscart_discussion.thread_id 
  AND cscart_discussion_posts.status = "A" 
  LEFT JOIN cscart_discussion_rating ON cscart_discussion.thread_id = cscart_discussion_rating.thread_id 
  AND cscart_discussion_rating.post_id = cscart_discussion_posts.post_id 
  AND cscart_discussion_rating.rating_value != 0 
WHERE 
  cscart_discussion.object_id IN (
    8862, 8860, 9845, 9853, 9843, 10065, 
    10101, 10172, 8878, 3315, 381, 480, 
    10067, 9851, 9842, 10063, 8861, 9849, 
    10076, 10945, 8864, 479, 10219, 3317, 
    9848, 8880, 8875, 8869, 8886, 9838, 
    8891, 10211, 8870, 9850, 8868, 10173, 
    8887, 8884, 10213, 10220, 10078, 8863, 
    9839, 10174, 8873, 9855, 8894, 10212, 
    8885, 8893, 8871, 10210, 9822, 3316, 
    8888, 9821, 8877, 9823, 10066, 10095, 
    10206, 10713, 9824, 10208, 556, 9854, 
    10139, 9844, 9840, 10946, 10096, 9841, 
    557, 10138, 558, 9852, 10217, 10142, 
    10141, 10140
  ) 
  AND cscart_discussion.object_type = "P" 
  AND cscart_discussion.company_id = 3 
GROUP BY 
  cscart_discussion.object_id

Query time 0.00152

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE cscart_discussion range object_id,company_id object_id 10 80 Using index condition
1 SIMPLE cscart_discussion_posts ref thread_id,thread_id_2 thread_id 3 mahm3t_cs443.cscart_discussion.thread_id 4 Using where
1 SIMPLE cscart_discussion_rating eq_ref PRIMARY,thread_id PRIMARY 3 mahm3t_cs443.cscart_discussion_posts.post_id 1 Using where

Result

product_id average_rating discussion_type discussion_thread_id
381 B 1658
479 5.0000 B 1701
480 B 1703
556 B 3397
557 B 3396
558 B 3395
3315 B 2212
3316 B 2213
3317 B 2214
8860 B 1988
8861 B 1989
8862 B 1991
8863 B 1992
8864 B 2023
8868 B 2019
8869 B 2020
8870 B 2021
8871 B 2022
8873 B 2018
8875 B 1996
8877 B 1998
8878 B 1999
8880 B 2001
8884 B 2004
8885 B 2005
8886 B 2016
8887 B 2017
8888 B 2006
8891 B 2010
8893 B 2012
8894 B 2013
9821 D 8432
9822 D 4178
9823 D 4198
9824 D 4199
9838 5.0000 B 3241
9839 B 3240
9840 B 3239
9841 B 3238
9842 B 5805
9843 5.0000 B 5803
9844 B 5804
9845 5.0000 B 5801
9848 B 4110
9849 5.0000 B 4111
9850 B 4107
9851 B 4108
9852 B 4109
9853 B 5494
9854 B 5802
9855 B 5496
10063 5.0000 B 4270
10065 B 4272
10066 D 4273
10067 4.9231 B 4274
10076 B 4669
10078 B 5497
10101 4.8333 B 4361
10172 B 4670
10173 D 4671
10174 B 5495
10219 D 5190
10220 5.0000 B 5932
10713 D 10584
10945 D 10866
10946 D 10871