SELECT 
  feature_id, 
  variant_id, 
  value, 
  value_int 
FROM 
  cscart_product_features_values 
WHERE 
  product_id = 10966 
  AND lang_code = 'de'

Query time 0.00089

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 95 Using where

Result

feature_id variant_id value value_int
129 5902
24 107
128 5899
127 5895
134 5961
22 99
42 145
20 6052 1.300
21 95
23 6273
30 6124
19 106 1.000
178 6311