Are runways booked by airlines to land their planes? Suppose Indigo lands at Indira Gandhi international airport and the arrival is schedule at 5:30 a.m. Is the runway to land on fixed by the airline.

If not please explain reason behind not to schedule the runway on which the flights will land.
No one can "book" runways. Traffic on a runway is managed by air traffic control, whose job it is to ensure a safe and expeditious flow of air traffic. Generally speaking, a place on the runway is assigned on a first-come first-served basis.

You may want to explore the air traffic control tag to learn more.