Most effective way is to merely google it. You will find tons of search results if you add token or coin along with the name you want to choose. Generally you will find duplicate names as that of your project but trust me if that project is not that successful you won't have much of an issue. Most of the projects don't bother about getting copyright much later until they have completed their token sale. Also main problem is that the ticker shouldn't be the same. So you can search for the ticker at Etherscan.io and see if there is some coin with a similar ticker because that can cause problems while sending and receiving payments.