Implement locks for GET request distinct by query parameter in Flask application

Question

I have setup a Flask server that serve a GET request like

@app.route('/foo', methods=['GET'])
def foo():
  id = request.args.get('key')
  """
    data = list_new_data(id)
    sync_new_data(data)
    mark_synced_data_as_read()
  """

  return 'success'

However, often time /foo?key=123 can be requested multiple times and if they happen to be running concurrently, chances are we will be duplicating new data. I'm wondering if there's a way to take out a lock distinct by /foo?key123 and fail or queue any subsequence /foo?key=123 coming after it?

Thanks