I love quick keys too. Personally I use finder windows accessed via command tab. I dragged my Downloads directory into the sidebar (it should be there already), or you can CMD drag the folder onto the toolbar at the top of the finder window. So: command-tab to finder, click Downloads in the sidebar or toolbar depending on where you put it, and viola! Alternatively, you could drag the downloads folder to the dock (it should be there already). Or, swipe 4 fingers down to reveal Finder windows (the "Mission Control" option in system preferences -> trackpad), then click desktop to select finder.
In Automator you could build a workflow and save it as a service. In Automator use open finder. Then select the service and assign a keyboard shortcut in system preferences -> keyboard -> keyboard shortcuts -> services. Good luck!