MAB941009

You can create a folder anywhere on your HDD, and drag and drop urls or WEBLOC files (From Safari's Address Bar) into the folder.
 
Create a new workflow from Templates/Files and Apps/File filter from keyword and open.
 
Under Basic Setup of the file filter you will put the keyword you want to use to search the folder.
Under the File Types, just drag one of the webloc files into the list area so the workflow knows it's only searching for those types of files.
 
Under Search Scope, drag the folder you created into the file area so it knows only to search that folder.
 
then hit save.
 
Now, when you type your keyword with a space and * ... it will show all weblocs in a list and you can select one to open, or you could even highlight one and hit SHIFT to quicklook it right from alfred.
 
If you type your keyword + a title you know is in there, it will show just that one ... using autocomplete and such.
 
 
I'm sure someone with advanced knowledge can tell you how to write a script to read the bookmarks.plist file safari stores in the library folder with parsing and all that, but it's a bit advanced for me personally.