SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f4bf558415308decbfed16b09ebd0382de9bb16b12776c88d4f12ebb56cab8f' 
  AND token = 'PaO51zSLSaXIDc52nXUir/7mZ4ob51TQsOr6cO+u2og=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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