There is no reliable to determine the age of mtDNA haplogroups (at least deep subclades like this) because the mitochondrial sequence is extremely short and uninformative. What is certain is that K1a is over 10,000 years old as it was found in many Neolithic sites and originated in the Middle East. The mutation for K1a10 could have happened any time since then, or might already have existed in a minority of people before the diffusion of agriculture.