@Meglet,
If you don't want the position of your carabiner attachment to the Small Cafe Bag webbing strap to shift, you can use one of the
OneTigris clips that @ceepee mentioned in
a reply post (#224) in the 2017 Wish List thread:
The usage case was for attaching an "O-ring" to the Synapse webbing, but these devices can also be rotated 90 degrees, or 45 degrees and click into a fixed position, if you want to attach to the webbing of your Cafe Bag, and not have the ring slide along the webbing, as a Carabiner would. Then just clip any keystrap onto the ring. Sorry I don't have a picture handy, but I tried this with a Cafe Bag.
Personally, I use a Mini Q-Kit to hold keys (and a small flashlight).
HTH
moriond