SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9ed5d88eab484dce3b421152ca7bb27d353f1218b36e86fb775601bb9167b3b2' 
  AND token = '0S1Tk48wXedxTCjTxkhAzAH7A9xpkmvGNDpq0RmpKL8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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