Production:
keytool -list -v -alias <your-key-name> -keystore <path-to-production-keystore>
For the debug key, look at https://stackoverflow.com/a/56091158 or run
keytool -list -v -keystore ~/.android/debug.keystore -alias androiddebugkey -storepass android -keypass android
Finally, the google play ones are on https://play.google.com/apps/publish/ > App signing