SELECT 
  booking_type 
FROM 
  ushop_booking_and_reservation 
WHERE 
  `booking_type` != 'N' 
  AND `product_id` = '517'

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "Impossible WHERE noticed after reading const tables"
  }
}