That's dereferencing of a glob reference, admittedly not a very common construct.

> ${*$ftp}{KEY}

That's accessing the %hsh for $ftp=\*hsh with $hsh{KEY}

> I've been programming in perl for quite some time now

you might have seen constructs like \*DATA before, those are glob references.

  DB<7> x \*DATA
0  GLOB(0x2d92040)
   -> *main::DATA
  DB<8> p ref \*DATA
GLOB
[download]

I hope it's clearer now.

Bareword filehandles and globs are historically linked. (Perl4 legacy IIRC)

EDIT

or better phrased the slot for filehandles in typeglobs has no own sigil like other types, hence you can only use *glob for referencing them.