Here's what I would do:
1) Create a new Service in Automator
2) At the top, select "no input" in "any application" from drop down menu
3) Search for "script" in the Library pane and drag over "Run Applescript"
4) Pase the following code in the box:
Code:
on run {input, parameters}
do shell script("open PATH_TO_FILE")
end run
5) Replace PATH_TO_FILE with the path to your excel file
6) Save it in ~/Library/Services (~ is whatever your Home folder is called)
7) Go to Keyboard pane in System Preferences
8) Click on "Keyboard Shortcuts", select "Services" on the left, find the service you just made, hit Enter and type in the shortcut you want
That should be it. Post back if you have any issues. Hopefully that works.