typescript type: define dictionary-like object type with a certain condition

Question

How can we define the type that follows the rules below with typescript:

1. has certain keys and values(say: key1 of srting type and its value as Date)
2. may (or may not) have any kind of key-value pairs for the rest

image:

{
 "key1": new Date(),
 "otherKey": "any value",
 ...
}

Thanks!