For a short term need where you'll turn on the heater when you need it and turn it off again shortly afterwards, you're probably going to be best off with some form of radiant heat. This type of heater will emit most of its heat as infrared radiation that you can direct toward wherever you're standing.
A typical radiant heater will have ceramic coated or metal coils (such as you would find inside a toaster or toaster oven) with a reflective surface behind that lets you direct the heat.
There are also in-floor (also in-ceiling or in-wall) radiant heaters that work similarly, but they require installation and more warm-up time before they will warm you.
You can also find heat lamps that fit in a standard light fixture that are designed to project radiant heat -- these are typically found in bathrooms to help warm the floor and yourself after a shower.
All heaters give off radiant heat to some degree, but radiant heaters are optimized to provide radiant heat that you can direct.
The advantage of a radiant heater is that it provides immediate heat that you can direct to exactly where you'll be standing and it can save energy since it doesn't need to heat the entire room when you only need heat for a short time. The disadvantage is that without heating the entire room, the radiant heat will only be felt on the parts of your body that are exposed to it, so, for example, if the heater was sitting on the counter (which I wouldn't recommend for safety reasons) and aimed at your face, you wouldn't feel the heat at your feet and the floor and other surfaces would still feel cold.
Keep in mind that any heater will use a significant amount of power (1500W is typical), so if you are planning on using any other small kitchen appliances at the same time (Toaster, Microwave oven, etc) and it's plugged into the same circuit as the heater, you might exceed the capacity of the circuit.
And, as with any heat generating appliance, operating it safely is important - don't put it where it can be easily knocked over or where pets or children can get close to it. Keep combustibles a safe distance from the heater (the instruction manual will have guidelines). Modern units will have tip-over and over-heat sensors, so avoid heaters of unknown age such as you might find at a garage sale.