Query to find all the Tables and Index with number of days statistics being old. Then run Update Statistics command to update statictics for optimized query plan.

SELECT
OBJECT_NAME(A.object_id) AS Object_Name,
A.name AS index_name,
STATS_DATE(A.OBJECT_ID, index_id) AS StatsUpdated ,
DATEDIFF(d,STATS_DATE(A.OBJECT_ID, index_id),
getdate()) DaysOld
FROM sys.indexes A
INNER JOIN sys.tables B ON A.object_id = B.object_id
WHERE A.name IS NOT NULL
ORDER BY DATEDIFF(d,STATS_DATE(A.OBJECT_ID, index_id),getdate()) DESC