Expose individual field values from grid as tokens

[Correction: it looks like I've got 3.18]

In my email I'm trying to send individual values from the grid, using this syntax:

%value[grid_questions][1]

(In this case "grid_questions" is the name of my grid.)

From this I'd hope to see, in my email, the option the user selected for the question having key = 1. But apparently this is not a valid construct. I just end up getting the entire grid, plus "[1]".

Is there any way to do this with Webform without custom coding? Am I just "off" on my guess at the syntax? Is there any in-depth documentation on this?