What type of plug is this, and can I replace it?

That is a twist-lock-style plug used with receptacles like this:

Receptacles are still available - I have no idea if it's code-allowed to use them, they're not at all common in my experience.

I would also be inclined to replace the plug for use with a normal common socket. Check the electrical ratings on the equipment for how many volts and amps it uses. These twist-lock receptacles I found go from 120V/15A up to 220V/20A so what's safe and proper would depend on your device/appliance.

Twist locks are a level above standard receptacles. There are 120v and 277v models the ground lug is on the opposite side of the ground blade I don’t see the fold but they are still indexed by width so they can’t be plugged in wrong. 4750 is 277v,, 4700 120v 15 amp. To convert to a standard duplex is fine like a 5362 receptacle and a 5266 cord cap would replace the twist lock if it is wired for 120v (I just happened to be in front of my plug bin)

I would expect to apply a 125% rating to the nameplate as a motor requirement, and NEC Table 210.21(B)(3) limits 15A plugs to twelve amps. I would use a nema 5-20 (20A/120v) or preferably a nema 6-15 (15A/240v) plug and receptacle.