SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd68a564c517ce6966bdfb6c75be9fe7024f084303490ea396ca03e82052791a' 
  AND token = 'Axsj69d+CKRnC6Ql/an8LjTnk1uDG/+7zIg11xUdEV4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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