SELECT 
  feature_id 
FROM 
  cscart_product_features 
WHERE 
  feature_id IN (550, 551, 552) 
  AND feature_type = 'E'

Query time 0.00015

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE cscart_product_features range PRIMARY PRIMARY 3 3 Using index condition; Using where

Result

feature_id
550