Does attribute_not_exists incur additional Read Capacity Units (RCUs) in DynamoDB?

I need to calculate the cost for using dynamoDB, I need to use attribute_not_exists func in Condition Expression to check for duplicates. I don't know if when using attribute_not_exists, it will generate Read Capacity Unit (RCU) or not?

When doing writes to DynamoDB, even with conditions, it only consume Write Capacity Units WCU, no Read Capacity Units RCU will be consumed.