SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3cf53bb186da61bb1a1e028da5a76aa1afb1dad04cd38715ef43c0477ce52b6f' 
  AND token = 'f8HkotlyYls/7nfnF9N2nzie2eDcoyE56dwF35zaOvY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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