Why does he look around? The standard explanation is that he wanted to be sure there were no witnesses to his killing the Egyptian. This fits in with several other cues in the text. Thus, he hides the Egyptian in the sand. He hopes no one finds out about it, and when he intervenes the next day and they refer to his killing of the Egyptian, he knows the matter is known and so he flees. Thus, it makes sense that even beforehand, he is checking that there are no witnesses.
Yet there is another, albeit less likely, possibility, but with nice homiletic implications. He could be looking around to see if anyone else is going to intervene. The Egyptian was striking the Hebrew, and Moshe hoped that someone else might intervene. But he looked all around and saw that there was no ish -- there was no one intervening. Thus, he stepped up and smote the Egyptian. In the aftermath, he thought to hide the body.
This is reading the pasuk in keeping with Hillel's dictum in Pirkei Avot 2:6:
Hillel used to say: A brutish man cannot fear sin; an ignorant man cannot be pious, nor can the shy man learn, or the impatient man teach. He who engages excessively in business cannot become wise. In a place where there are no men strive to be a man.When he tries to intervene in a similar situation the next day, between two Hebrews, he is asked what right he has to do so - who appointed him. But this for another post.