If you have the Powerpack for Alfred 2, you can create a workflow like this:

Hotkeys have a short delay by default, but you can reduce it by changing the trigger behavior:

Another option is to use a private.xml like this with KeyRemap4MacBook:
<?xml version="1.0"?>
<root>
<vkopenurldef>
<name>KeyCode::VK_OPEN_URL_FINDER</name>
<url>file:///System/Library/CoreServices/Finder.app</url>
</vkopenurldef>
<item>
<name>shortcuts</name>
<identifier>shortcuts</identifier>
<autogen>__KeyToKey__ KeyCode::F12, ModifierFlag::NONE, KeyCode::VK_OPEN_URL_FINDER</autogen>
</item>
</root>