SELECT 
  count(*) 
FROM 
  cscart_ec_table_booking_system 
WHERE 
  booking_type != 'N' 
  AND product_id = 270023

Query time 0.00038

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}

Result

count(*)
0