OneTravel indeed offers a credit card to their customers. There are three versions of the card: OneTravel Credit Card, OneTravel Visa® Credit Card, and OneTravel Visa Signature® Credit Card. All three cards are issued by Synchrony Bank. The first card, OneTravel Credit Card, can only be used at onetravel.com, the other two cards can be used everywhere Visa cards are accepted. The cards will allow you to earn points for booking flights at onetravel.com and other services offered by the company. All earned points can be redeemed at onetravel.com only.
Since your credit is fair, you may qualify for the Visa card or for OneTravel Credit Card. Note that you cannot choose which card to apply. The issuer will decide which card to issue after you submit your application. You can also earn OneTravel Rewards by creating an account with them. The membership is free.