SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27ea741db0b3be894f3bfbf953a044978862dfc7df66847f846597f86932753a' 
  AND token = '32aUmPYx1uX+TCAYnc2beQ7hF3Vlyi+UcP1f48tNcnU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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