gistfile1.txt

curl --request POST \
  --url https://auth-dev.mozilla.auth0.com/oauth/token \
  --header 'content-type: application/json' \
  --data '{"client_id":"ID","client_secret":"SECRET","audience":"https://manage-dev.mozilla.auth0.com/api/session_testing","grant_type":"client_credentials", "scope": "test"}'

Result if `test` exists and is granted to your client id:
{"access_token":"SECRET","expires_in":86400,"token_type":"Bearer"}


If not:
{"error":"access_denied","error_description":"Client has not been granted scopes: test"}