While we explore other solutions for this, I will bring up a workaround for lenses that mostly works.
You can create a bang that opens a lens with the following template:
/search?q=%s&l=LENS_INDEX
Where LENS_INDEX is a number starting from zero, as ordered by the dropdown:

For example, this will create a bang that will open the second lens in this list:

The caveat is that if you reorder your lenses, this bang will go to whichever lens is in the second spot, not the original one you intended. So if you do this, the bang needs to be updated, if you want it to go to the same lens.