Slow Performance of Parametrized Query in Excel due to Parameter Datatype
The issue appears to be parameter sniffing as the link you provided indicates.  I'm not sure how to fix the issue in Excel, but if you can figure out how to specify the datatype when it's creating the parameterized statement, that would fix it.  

You have a few options that can help with the issue on the SQL Side.  I would only choose one of them and each of them have their price.  I think the best solution would be to use a stored procedure to mask it, but you will know your environment the best. 

If you can modify the source table:


add a computed column of the NVARCHAR data type, equal to the RunID column, persisted.  Increased storage and a minor hit when RunID is inserted or updated but cleanest solution overall.  Modify your query from excel to use the computed column.
change the data type of the column to NVARCHAR.  This would probably impact everything in your environment, but would be the easiest to implement.
Create a stored procedure that accepts an NVARCHAR as an argument, then cast that to a different variable but with the correct data type, then return the desired results.  Clean solution, but requires a stored procedure be created and maintained.  


To answer a question below (can't add a comment to my own answer, apparently).  

You would create a stored procedure that accepts the NVARCHAR data type as the argument, then explicitly cast that value to a varchar type and use that in the query.  It saves the execution plan from doing a conversion on every row.  So something like this 

CREATE PROCEDURE sptest (@inputparam NVARCHAR(50)) 
AS 
DECLARE @queryparam VARCHAR(50) = CAST(@inputparam AS VARCHAR(50)) 
SELECT * FROM tabletest WHERE columnvalue = @queryparam