How can't Optimize the query
It seems (from the separate Filter operator) that the columns involved are currently typed as large objects (LOBs) e.g. varchar(max). Fix this by giving the columns a more suitable type (assuming the data involved will fit in <= 8000 bytes) and using the correct modelling hints (assuming you are using something like Entity Framework). With non-LOB types, the engine will be able to push the Filter conditions into the Index Seek, which can be made more efficient still by careful indexing (non-LOB columns can be index keys, LOB columns cannot). If the optimal plan shape for different variable values varies, adding an OPTION (RECOMPILE) hint to the query or using dynamic SQL may pay dividends as well. Using the recompile hint allows SQL Server to generate an optimal plan for the current variable values on each execution, at the cost of a recompilation.