No tax benefits are available regarding capital gains if the money is used to prepay an existing home loan except to the extent available under section 80 C for repayment of the principal amount of the home loan taken for a residential house up to Rs 1.5 lakh every year. This includes other items like provident fund contributions, equity-linked savings scheme (ELSS), life insurance premiums, tuition fees, Public Provident Fund (PPF), etc.
Since you are selling the plot after holding it for less than 24 months, the profits of Rs 5 lakh shall be treated as short-term capital gains. No exemptions are available regarding short-term capital gains under income tax laws. The short-term capital gains so earned are added to your regular income, and you will have to pay tax at the slab rate applicable to you on such short-term capital gains. I would advise you to hold the plot for at least 24 months to become a long-term capital asset, and the profit made gets treated as long-term capital gains.