I suppose that you want to retrieve a single entry/line from the VARA object unsing either the script function GET_VAR or curly brackets.
Well, the script function - as you might have seen in the documentation - needs to be configured with a key when you want to access a static Vara object. However the key is not required if the vara object is defined to "no scope".
Let me compare the VARA object with an indexed database table: how do you retrieve a single row? You have to identify it by e.g. using the row id - which is very similar to our key. Nevertheless it's possible to scan the entire VARA object: PREP_PROCESS_VAR is the way to do so.