SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c16d9cf4927bb44c9742bb1030e455396966e7a092e6ce46ad2763944d746f2f' 
  AND token = '1uHYsJc57OZcBtWZiyKb0NHSkZrt6bdjKoMh0IcIfCo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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