How many orders of O'Sullivan Plantations 2-Door Library in Landvery Oak in central superstore were shipped through the shipping mode with the fastest delivery speed?
'O'Sullivan Cherrywood Estates Traditional Bookcase' is the "Product Name"; shipping mode with the fastest delivery speed refers to "Ship Mode" = 'First Class'
SELECT COUNT(DISTINCT T1.`Order ID`) FROM central_superstore AS T1 INNER JOIN product AS T2 ON T1.`Product ID` = T2.`Product ID` WHERE T2.`Product Name` = 'O''Sullivan Plantations 2-Door Library in Landvery Oak' AND T2.Region = 'Central' AND T1.`Ship Mode` = 'First Class'