A persistently itchy moles can be indeed warning sign of a melanoma (ordinary moles aren't usually itchy).
Also, knowing the fact that melanoma can develop from a mole located at the soles and toe fingers, and that this place has frequent frictions and trauma, you should ask for further examination or even excision.
It will be good this mole to be first checked with dermatoscope, an instrument that can help your dermatologist to distinguish benign from malignant lesion (it will help your doctor to decide if the mole needs to be exceeded or left). It is especially of aid in the diagnosis of malignant melanoma.
Melanoma changes don't take long time!
Waiting for your post!
Best wishes!
Marija