Setting the emoji font

[YTG 1234]

I want to use emoji within markup, and I can see in the output log that 
Lilypond can't find a character in its default emoji font (Symbola). I 
can't figure out how to override the default font.

%%%
\markup {
    "🔒" %% This character isn't be found
}

%%%

I saw an old thread recommending to use \override #'(font-name . "..."), 
but that doesn't seem to work in modern versions (I'm on 2.25.11). 
Overriding the serif font doesn't work either, as I don't think Lilypond 
tries it at all.