One First author paper, what are my prospects in academia?
To be frank, in molecular/cell biology your chances are rather slim. The 'standard' is almost 3-5 papers from your PhD which can be expected to be out by the end of your first postdoc plus some output from your postdoc. Of course, it is stupid to judge people only by their paper metrics, but this is what very many people in academia do. If you are lucky, you find a person who is not that quick with her judgement and searches for the hidden gold, carefully reading your letter and CV and the reference letters or is giving you a chance and invites you for interview. That can happen (happened to me once), but is rather rare.

Chances are even lower if the hiring process involves a committee panel or external reviews (as for grants or scholarships). Competition is often high, so you will usually only have a chance when you get very good/top marks from all reviewers. Because if there are three candidates who get 3 A+'s and then there is you, and even if just one of the three reviewers was only looking at publication output (chances for that will be veery high) and gave you a B or C, then you are already out and the decision will only be between the top-rated candidates.

On the other hand, a combination of a convincing letter AND the luck of being at the right time ready for the right job AND a bit of luck of hitting a person who is not overemphazising your publication output might put you into your 2nd postoc. Your chances are low but not zero.