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SELECT 
  pf.feature_id 
FROM 
  cscart_product_variation_group_features AS gf 
  INNER JOIN cscart_product_filters AS pf ON gf.feature_id = pf.feature_id 
WHERE 
  pf.feature_id > 0 
  AND pf.filter_id IN (10) 
LIMIT 
  1

Query time 0.00041

Explain
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	pf	const	PRIMARY,feature_id	PRIMARY	3	const	1
1	SIMPLE	gf	ref	PRIMARY	PRIMARY	3	const	1	Using index