I created an android app that shows google map using Google Map api V2 and it works well with me in my mobile.
But when I uploaded the apk of this app to (Google play store
This is simple method. Select your project->Right click->Export android application. Fill all requirements. When exporting it will show your SHA 1 finger print. copy that and paste it along with package name in google console. You can see Certificate finger prints in screenshot.Use that SHA1 key.