The song is "Spoutnik" by MIRWAIS.
It is listed as "Crazy Horse Paris Spoutnik" on websites unrelated and existing prior to Three Days to Kill, and at the end of the film credits and on websites related to the film as follows:
Music Crazy Horse : SPoUTNIK
(c) TORA BORA / CRAZY HORSE PRODUCTIONS
(p) CRAZY HORSE PRODUCTIONS
The song does not appear in producer Mirwais Ahmadzaï's discography.
As of this writing, "Spoutnik" is not for sale individually or as part of Three Days to Kill's official soundtrack, but can be streamed or downloaded here along with other tracks produced by/for Parisian cabaret Crazy Horse.
The dancer in the film is performing a modified version of a two-person sequence from Crazy Horse circa 2012, which can be seen in Youtube trailers here and here (warning: nudity). These trailers are for "FEU: Crazy Horse Paris", a theatrical version of the cabaret show which included the sequence.
A 2011 documentary about Crazy Horse (trailer here) (warning again) details the production process for sequences and their original songs, for which dancers sometimes record their own vocals. It's likely that Mirwais was commissioned to make a song for the sequence called Spoutnik, incorporating vocals by one or both of the dancers. (Notice the dancer is lipsyncing in Three Days to Kill; she's performing her own song.) Where the song and the sequence are a package fully owned by Crazy Horse, until Three Days to Kill there was no need to assign further credit. Credit seems to have finally been assigned as we see in the film per the particulars of Hollywood's code of credits.
Interestingly, neither dancer gets song credit, nor does the dancer in the film get a cast credit.