Khanom krok looks light because each piece is the size of a thumb. The maths does not care about the size. Rice flour batter is 130 calories per box, the coconut cream topping is 120, the sugar is 80 and the oil brushed into the pan is another 35. That is 360 for something you finish walking from the stall to the motorbike. A box every morning with your coffee is 2,500 calories a week, about a third of a kilo of fat a month.
The MGR calorie table lists 2 pairs at 210, which puts a pair at 105. That is a big pair. Most market boxes have 8 smaller shells and the batter is thinner, so 90 per pair is closer to what you are eating. Either way, one box is a dessert, not a snack, and 48g of carbs with almost no protein means it does nothing for hunger. You will want lunch at the normal time.
There is no low calorie khanom krok. The whole thing is coconut fat and rice starch, and the version with taro or corn on top is the same number with 5 extra calories of vegetable. What works is buying half a box. Four shells at 180 calories with a black coffee is a reasonable morning. The full box plus a cha yen is 660 before 9am.