SELECT p.product_id, pv.value_id, GROUP_CONCAT(pv.value_id) as value_ids FROM product p
INNER JOIN product_to_value pv ON (p.product_id = pv.product_id) GROUP BY product_id 
HAVING ( FIND_IN_SET( 10, value_ids ) >0 ) AND ( FIND_IN_SET( 6, value_ids ) >0 OR FIND_IN_SET( 8, value_ids ) >0 )

SELECT product_id FROM product_to_value WHERE 
product_id IN 
(SELECT product_id FROM product_to_value WHERE value_id IN (6,8) GROUP BY product_id)
AND
product_id IN 
(SELECT product_id FROM product_to_value WHERE value_id IN (10) GROUP BY product_id )
GROUP BY product_id