Erotic massage studios in Paris often advertise under the name “massage naturiste”. Salons offering massage naturiste in Paris and which run their own websites are Nuru Spa (http://www.nuruspa.fr/) on 34 Rue Dussoubs and le Bain des Sens (https://www.massage-vip-paris.fr/) situated at 38 Rue de Tocqueville, close to metro stations Villiers and Malesherbes (line 2 and 3). In these places you can usually get a happy ending by hand job but they will not say it out loud and it will be offered or need to be negotiated once you are in.
Getting an erotic massage in Paris can get a bit tricky since the authorities can treat massage parlors as brothels and as such deem them illegal when they find out they offer more than the regular relaxing (body to body) massage. Whenever a parlor opens up it can shut down pretty quickly. That doesn’t mean it’s impossible to get a good rub down in Paris, but you might have to look also for independent erotic masseuses advertising on the internet, or via word of mouth, so looking up some on erotic forums could be a good start. There are a few Asian massage parlors on Rue Boci, which have Nuru, Tantra and Thai massages on the menu and can offer a good remedy if you’re desperate for some happy ending action.