Our empty lot neighbor claiming an easement that we didn't know about

[louisaip]

Recently we've been bothered by our empty lot neighbor claiming he has a right to use our front porperty to access across his property. We bought our house around 2 years ago. The title is clean. About 1 year ago, we saw strangers walk through our property to next lot. (Our next lot neighbor has a front street footage of 336 ft, while our front street footage is only 107 ft long). We are located on the hillside in California. Since our property is well developed( 27 years). He rather walk through our lot to get to his lot which is a little bit down slope from the street frontage. He is trying to sell his land , and showing it to real estate agents...

An easement for ingres and egress for driveway purposes and the installation and maintenance of utilities over, under and across the following described parcel of land: ....
......which describe our whole street frontage and side..

This easement was never in our title, and even if this easement is legal, his lot had been empty for 27 years, can he still claims this easement. Also the easement said for driveway purpose only, since he hasn't use it for more than 20 years, will this easement be extinct?

Thanks in advance for your help!

Desperately seekly advise
Louisa Ip