SELECT 
  feature_id, 
  variant_id, 
  value, 
  value_int 
FROM 
  cscart_product_features_values 
WHERE 
  product_id = 3318 
  AND lang_code = 'en'

Query time 0.00045

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 65 Using where

Result

feature_id variant_id value value_int
127 5895
128 5899
129 5903
30 6131
42 6256
149 0 5707275102877
124 0 5707275102877
24 107
135 5968
136 5975
135 5965
136 5974
136 5977
176 6264
136 5976
178 6317
136 5973
136 5972