Your chances of a true "keloid" is very slim, however, there is some chance of a visible scar. This depends on how your perform the epicanthoplasty or medial canthus surgery. This procedure is common in my practice so my first comment to you would be, more so than a keloid, you could have an incision that could be visible for a few weeks to a few months. This depends on:
1. Do you have a darker complextion vs. fair/pale? If so your chances of visible scar are slightly higher
2. Is your skin thicker than average? If so, chances are slightly higher.
3. How heavy and big is this fold?
The incisions can often be planned in such a way that they are less visible or hidden. Are you having this done along with an upper eyelid blepharoplasty?
Medial canthoplasty or epicanthoplasty incision are made so many different ways and should be tailored to the patient. It's hard to describe them with text.
Best of luck
Dr. Chase Lay