Macbook Serial Number activated? how to know?

Hi community, I am going to buy a Macbook, if I check the serial number in my iPhone coverage application (dark screenshot) , I get a limited warranty date in less than one year, if I check the same serial number in apple website, I get a different information (Purchase date not validated). How can I know if this product was already activated with an iCloud account or not? How can I know if I buy it, if I can put my iCloud and extend warranty for two years? Thank you!!