SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '12dc001583999da865c8482e134ba469209165dae7de80908447fe73b14fc300' 
  AND token = 'hGKT/GykCIwJD8tyO/eOHZGcsquEaL8grvOfzHWo/n0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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