SELECT 
  feature_id, 
  variant_id, 
  value, 
  value_int 
FROM 
  cscart_product_features_values 
WHERE 
  product_id = 9857 
  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 51 Using where

Result

feature_id variant_id value value_int
129 5902
30 6221
127 5895
128 5899
175 6236
173 6228
169 0 1.010
173 6229
171 6225
170 6219
174 6232
174 6235
174 6233
178 6327