If you’re talking about the WordPress custom fields (no external resource like plugin etc.), then the answer is: No, unfortunately not.
The meta box calls has_meta and list_meta – and none of these functions provides suitable filter/action hooks.
The custom fields are ordered by meta_key,meta_id.
Of course, you can set up your own meta box.
All you need to change is the call of has_meta – and adapt the SQL ORDER BY clause.