Indian Cricket Team is controlled by BCCI (Board of Control for Cricket India. And it doesn’t come under or controlled by Government of India. So there is no age limit for a cricketer or any sports person in India. You can debut at any age, if your fitness, stamina or recent performance are very good.
The oldest cricketer to debut for India was Rustomji Jamshedji, at the age of 41 years and 27 days in 1933 against England.
But it was the phase even before Independence. Now a days, there are lots of criteria for you to clear for being selected in Indian Team.
Domestic Performances (Ranji Tournament, Syed Mushtaq Tournament, and IPL)
Yo-Yo Test (test of fitness and stamina). You can train yourself at National Cricket Academy, Bangalore, once you get the nod from BCCI Selectors. Now this test is mandatory to clear if you want yourself to be selected in squad. Even Suresh Raina and Yuvraj Singh are out of the team, as they were unable to clear this test (but now, Raina has cleared it after extensive training at NCA)
Even the oldest cricketer to play for India was Vinoo Mankad, at the age of 41 years 305 days. His last test was on 11 Feb 1959, against West Indies. But it was also far back from now, as we can see there are lot of competition for each place in our Team. We have back up for every position who can perform perfectly well. Even we have tremendous captain backup as well.