Verify the licence on the register
A real operator names its regulator and licence number, and that number resolves on the regulator's own site. lucky-bet.us, by contrast, lists Test Test as its WHOIS owner and a proton email. That alone is disqualifying.
Read the payout complaints
Search the domain on AskGamblers and Trustpilot. A documented, escalated unpaid win, like the Curacao 1600 dollar case, is a serious signal. So is a blacklist entry such as the GPWA case against luckybet33.
Check the age and the SSL
A brand new domain with DV-only SSL and gift-card payment tags is a classic fraud profile. Cross-check WHOIS dates against the operator's claimed history.