Is there any snap available in SnapLogic to do following
Is In-Memory Look-Up useful for this?
No, In-Memory Lookup
snap is used for cases where you need to look up the value corresponding to the value in a certain field of the incoming records. For example, say you want to look up a country name against the country ISO code. This snap generally fetches the lookup table once and stores it in memory. Then it uses this stored lookup table to provide data corresponding to the incoming records.
In your case, you have to use the Join
snap and configure it to an inner join.