SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '33fa81fc611264438150e596c91a46d60b219098fea0737c54d035100feb0fca' 
  AND token = 'dmvm4yowM5hRaLOZUxNtOwmHhNzKFKjg7gegyQr6saE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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