3 things will give you the biggest advantage
- Directional microphone cardiod pattern being the best for this scenario
- Quiet keyboard - sounds silly but there are keyboards that are much quieter than others
- Gate - a piece of equipment that mutes the sound when it's below a certain threshold or volume. i.e. when you aren't talking it's muted.
Personally I've found that Dynamic vs Condenser microphones pick up far less because their sensitivity is usually lower. This is why often the "headset" mics work well in only picking up the voice and nothing else.
Another factor in this particular scenario that can also make a large difference is background music. If there is music fed into the stream/video it will likely cover over many background noises provided they aren't very loud.