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SELECT 
  feature_id, 
  variant_id, 
  value, 
  value_int 
FROM 
  cscart_product_features_values 
WHERE 
  product_id = 9849 
  AND lang_code = 'en'

Query time 0.00042

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	60	Using where

Result

feature_id	variant_id	value	value_int
30	240
42	6257
127	5895
128	5899
129	5903
24	109
135	5964
136	5975
135	5965
136	5976
178	6308
136	5974
176	6259
136	5973
136	5972
136	5977