SELECT 
  feature_id, 
  variant_id, 
  value, 
  value_int 
FROM 
  cscart_product_features_values 
WHERE 
  product_id = 10142 
  AND lang_code = 'de'

Query time 0.00058

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 51 Using where

Result

feature_id variant_id value value_int
23 6297
134 5961
127 5895
129 5902
42 146
75 243
128 5899
19 106 1.000
24 107
30 240
20 6052 1.300
22 99
21 95
178 6308