SELECT 
  count(*) 
FROM 
  cscart_booking_and_reservation 
WHERE 
  booking_type != 'N' 
  AND product_id = 15367

Query time 0.00013

JSON explain

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