SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '923a2579872ca1809a54b79ad9fa806147cd1c510900f535d4ae366f338dcfc9' 
  AND token = 'wHuYEUefoXOPtCZ2PCbooSBkMGXPSLL5lUKxV+ZB7N4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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