SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1c3bbdbfc92b8f53d119a475572157f67cf5aa11e784de3bd1bd7d85ba869836' 
  AND token = '8LSd67bm5wKF0pvCTPIXP9UMQxgabozc2Vx0IbSzq8w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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