SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '894ca463efb19ab8888214e2001cb5b25c2395a9923ecea3d3907a2c6a6b7be2' 
  AND token = '5pxQ4N48Sob+uI+F/YTKFhVW4bLHUEvMkUhzsTpZa5w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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