If the potting soil was too wet for a while, then it might be fungus gnats, but they don't really look like that, although a magnifying glass would be useful for you to use. Image and information on managing fungus gnats here
It might just be aphids though, so using a proper insecticide that treats for those might be more effective, particularly a systemic one. I am curious as to why you are keeping this plant 'mostly in the dark' though - those sorts of conditions do not make for healthy plants.
Further to your comment: first, direct sunlight is not the same thing as bright daylight or even just daylight. Most (though not all) indoor plants do not appreciate hot sunlight through a window, but may tolerate some sunlight in winter; otherwise, the general rule is to give them bright or medium daylight, depending on the plant and its requirements. In the case of Kalanchoe blossfeldiana, it does appreciate some sunlight, particularly in winter, see here https://www.thespruce.com/growing-kalanchoe-plants-1902982.
In respect of the insects present on the plant, they do not look like scale insects, but, as I said, might be aphids or fungus gnats. Scale insects are usually affixed to the plant and don't move, although the 'crawlers' (baby scale) look different and do move, but they don't fly. Which insecticide you can use depends on what's available where you live - I'm in the UK, so what's here might not be something that's on sale where you are. That said, most insecticides do treat for aphids as a minimum, but all should carry a list of precisely what they do treat usually on the exterior packaging - the main difference is between systemic or contact. The latter only treats what's on the plant when you spray (like a home made soap spray does) whereas a systemic gets into the sap stream of the plant and keeps the bugs off for up to two weeks.