As others have said you need a fast lens for low light conditions. I personally am hesitant to shoot wide open because you have such a short DOF & focusing is difficult in low light. Here are a couple I took with f1.4 lenses shot @ f2 & my ISO maxed out @3200.
1. 58mm f1.4, squeaked out a shutter speed of 1/80s.
2. 50mm f1.4, I only got a shutter speed of 1/25s & you can see a lot of motion blur.
3. Now this shot was taken with a 45mm f2 lens wide open & I got a shutter speed of 1/50s.
These are all manual focus lenses that I use.