Online IMEI websites are seldom reliable (which is why so many have paid options). The only way to check is to look at it's physical condition.
There's an American website, swappa.com/esn, that is reliable in checking whether the phone is stolen or not (but you'll have to use a VPN to use the service as it's geo-locked).
Also check using:
www.icloud.com/activationlock
ting.com/byod
tmobile.com/verifyimei.aspx