May I use my former-yet-active email address of an institute as a contact channel in my current CV?
I can see no legal or ethical problem with using an email address from a former institution, as long as you are clear about your current affiliations in your communications.
That said, there may be better options:

Professional societies often offer an option of an email address. As a roboticist, for example, you can almost certainly affiliate with the IEEE, whose excellent email service I use myself.
One of your former institutions may offer an alumni email address (or at least forwarding service). I believe this is more common in the US than Europe, but it's fairly arbitrary which institutions do and do not offer this.

Both of these can typically be set up very quickly and also have the advantage of being permanent, even when you change institutions.