Yes, you can get a mortgage loan on a property with 89 years left on the leasehold. Among other requirements the leasehold must be valid for at least five years beyond the term of the loan for conventional financing and at least ten years beyond the term of the loan for FHA financing.
If you have a home on a land lease, then yes you can get a loan. Since you have a vested interest in the property beyond the lease (i.e. your home that is physically attached to the property) you can get a loan. The term of the loan must finish before the lease expires.
The problem can be in finding a lender that will handle the loan. Another complication can be the appraisal. Typically, an appraiser must find comparable sales that were also on similar leasehold arrangements. Depending on the type of lease, this could be difficult.