SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff1a4d4f984a9dd2a36e5958a520cf94383aa04fee94200296dd19c24776a878' 
  AND token = 'U/893nwAeSKxtktQrMNseEvpcVcEFGUPl7ocoyCnGrw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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