you dont need to check if position is empty while you checking numbers in field list .
you dont need to check position = FIND_IN_SET....
. it will return the value where 1 is in position.
you need to do it like that:
SELECT `id`
FROM `table`
WHERE `status`=1
AND FIND_IN_SET( 1, `position` )
OR FIND_IN_SET( 2, `position` )