Tokens available in views
The tokens available when rewritting the output of a field correspond to the values of the other fields you have selected in the view. They must also be above the field you are rewritting in the field order.

In order to get the URL, you should add a node path (or link to node) above your current field and mark it as "hide from display".

The token will now be available!

PS - If you want to link to the node's url, you can always just select the option to display the field as a link to its node.