How can I find out if there's an EASA STC for something that has an FAA STC? I want to purchase something for my Cessna from a US web shop. 
The part has a Supplemental Type Certificate (STC) from the FAA, but I don't find any information about the EASA equivalent. 

Is there any database to check this?
Unless I am reading the document incorrectly, EASA and the FAA have a reciprocity agreement since 2011 recognizing each other's findings and approvals. That means an FAA STC approval is good in EASA countries (except the ones that are not EU members) and vice-versa.