Is it going under the process to use icons and logo (logo of visa for payment) in low fidelity wireframes ?
The main aim of low fidelity prototyping is to not spend superfluous time on details that don't affect the Information Architecture or structure of your page.
While there is no harm in putting a logo at this stage, by putting the logo of VISA, you have restricted the payment gateway to only VISA. If that is what you were going for, I wouldn't worry about the logo much. However, by creating a generic credit card layout, there would be no loss of information either.
That being said, I believe that it is necessary to add icons when and where required. When you have 10s of 100s of wireframes, there is a chance that you can forget what a crossed box represented. Presence of icon indicates functionality, which should not be compromised with at any level of prototyping!
The point of low-fidelity is that you want to test whether your designs communicate what it needs to. Icons are a vital part of that story. However, to prevent stakeholders from falling over the details, your main objective is to keep these brand sensitive aspects as generic as possible and simply focus on what is it communicating. Adding the branding comes much later.
At this point, icons will consist of generic icon sets (think FontAwesome, Ionicon) as placeholders to convey the message it needs to send, but not have the burden of being styled with any brand specific imagery. Having icons instead of a placeholder rectangles is important; you need to test whether the icon does its job of being a scanning-anchor. The same can be said for the logo.