SELECT 
  rating_value, 
  COUNT(1) count 
FROM 
  cscart_product_reviews 
WHERE 
  `product_id` = 132 
  AND `status` = 'A' 
GROUP BY 
  rating_value

Query time 0.00028

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE cscart_product_reviews ref idx_product_id idx_product_id 3 const 1 Using where; Using temporary; Using filesort