SELECT 
  feature_id, 
  variant_id, 
  value, 
  value_int 
FROM 
  cscart_product_features_values 
WHERE 
  product_id = 3320 
  AND lang_code = 'de'

Query time 0.00046

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 79 Using where

Result

feature_id variant_id value value_int
30 6131
136 5975
136 5972
176 6269
42 6256
176 6266
176 6267
176 6272
127 5895
128 5899
129 5903
135 5968
135 5965
136 5974
24 107
136 5977
178 6317
136 5976
136 5973
176 6268
176 6265