Hello, My dog has not received any of his shots, and he's 5 years old. he's a chihuahua mixed. by appearance, he looks healthy. i was wondering if i can still take him to a vet and get hims his shots?

You certainly should get his shots, if he has no shots then he has no immunity to things like Parvo which can kill him also I'm pretty sure that most states require Rabies shots. 

Some organizations or even vets have shot clinics where you can get the shots quite inexpensively at certain times, you should look into this.  But certainly do the right thing for your pet and protect him from dangerous diseasesl