SELECT 
  feature_id, 
  variant_id, 
  value, 
  value_int 
FROM 
  cscart_product_features_values 
WHERE 
  product_id = 3322 
  AND lang_code = 'en'

Query time 0.00057

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE cscart_product_features_values ref lang_code,product_id,product_id_idx,product_feature_idx product_id 3 const 63 Using where

Result

feature_id variant_id value value_int
42 149
30 6131
127 5895
128 5899
129 5903
176 6260
24 107
136 5976
136 5972
135 5967
176 6262
135 5968
176 6270
135 5963
176 6271
135 5964
178 6317