Tokens that has already been listed in exchanges are mostly posted in Coinmarketcap. But there are also a lot of coins that are on exchanges but wasnt applied to coinmarketcap so what I do it visit the telegram and twitter account of the coin to see their announcements about where they are listed.
You're mistaken mate, only coins that have a minimum market volume of 100k within 24hrs will be listed on it. Some coins can be track by using BitUniverse apps which you can find there what exchanges that is currently listed. In other way also, by visiting their sites and telegram participation.