SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8cc79e4ba36b23260ecefca46c93e98751bc33fde74069925c8568672f008ff' 
  AND token = '+e5hPVB7uW6ZhRaHGg3Vx0kuXAYjEmrBXsbFg1HVU7E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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