What I suggest that you do is first go to https://www.bhphotovideo.com/c/buy/SLR-D...
to see what's on the market at your price range. On the left, you will see an option to select mirrorless camera or DSLRs. Both are equally good types of cameras.
Here's a link to dpreview.com's app that allows you to see the difference between various cameras at various ISO settings. This web app will allow you to see which cameras have the least amount of noise. https://www.dpreview.com/reviews/image-c...
One thing that you're likely to notice doing this research is that the cameras with the best high-ISO performance are those with fewer but larger pixels.
If you can increase your budget to about $750, you'll end up with one of the absolute best cameras for low light: the Pentax D-70.
What makes a $750 Pentax DSLR superior to a professional $6,000 Canon or Nikon is that only Pentax has in-body image stabilization. Since the sensor is doing the stabilization, this means that every single lens you use (including lenses from the 70s) will be stabilized. Imagine a $400 50mm f/1.4 on a $6,000 Nikon D5 in a dark situation that requires an exposure of 1/60th @ f/1.4. With a Pentax K-70 and a $50 used 50m f/1.4, you now have the ability to shoot at 5.5 stops lower ISO. This means that if with the Nikon you had to be at ISO 6,400, you could be shooting with the Pentax at only ISO 125. Because the Pentax can use such a massively lower ISO, it simply isn't possible to get as good of a shot with a $6,500 Nikon D5 kit.
Pentax also uses sensor shift in what's called pixel shift. Take a look at the Bayer pattern of a modern CMOS sensor. It's an array of red, blue and green pixels. But what's interesting is that there are more red & blue pixels than green ones. Pixel shift moves the sensor 1 pixel at a time, takes three shots, and then combines them into one image with an increase in color and sharpness that's not possible with any other DSLR at any price.
If you're into astrophotography, Pentax uses its pixel shift technology in what they call astro tracer. When taking shots of stars, you have to keep the shutter speed no longer than 30 seconds. Anything longer than 30 seconds, and the stars will show up as smudges or long trails due to the rotation of the Earth. Astro Tracer moves the sensor during the exposure to cancel out the rotation of the Earth. Net result is that you're no longer restricted to 30-second exposure with f/2.8 lenses at ISO 3200. Now, you can use a cheaper kit lens at f/4, lower your ISO and end up with amazing sky shots. If you used an f/2.8 lens, then you could lower your ISO even further and get Milky Way shots that would require motorized tripod heads with any other camera.
If you can't afford a $750 Pentax K-70, then get a used K-50 on eBay for under $300 with a kit lens. Even though it's discontinued, the K-50 is still a better camera than the new entry-level DSLRs from Canon or Nikon.