try these two, searches plan cache for your index name

WITH XMLNAMESPACES (DEFAULT 'http://schemas.microsoft.com/sqlserver/2004/07/showplan')

SELECT

DB_NAME(E.dbid) AS [DBName],

object_name(E.objectid, dbid) AS [ObjectName],

P.cacheobjtype AS [CacheObjType],

P.objtype AS [ObjType],

E.query_plan.query('count(//RelOp[@LogicalOp = ''Index Scan'' or @LogicalOp = ''Clustered Index Scan'']/*/Object[@Index=''[MyIndex]''])') AS [ScanCount],

E.query_plan.query('count(//RelOp[@LogicalOp = ''Index Seek'' or @LogicalOp = ''Clustered Index Seek'']/*/Object[@Index=''[MyIndex]''])') AS [SeekCount],

E.query_plan.query('count(//Update/Object[@Index=''[MyIndex]''])') AS [UpdateCount],

P.refcounts AS [RefCounts],

P.usecounts AS [UseCounts],

E.query_plan AS [QueryPlan]

FROM sys.dm_exec_cached_plans P

CROSS APPLY sys.dm_exec_query_plan(P.plan_handle) E

WHERE

E.dbid = DB_ID('XPLAN') AND

E.query_plan.exist('//*[@Index=''[your index name]'']') = 1

-- OR (BETTER)

SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED

DECLARE @IndexName AS NVARCHAR(128);

set @IndexName = your index name';

-- Make sure the name passed is appropriately quoted

IF (LEFT(@IndexName, 1) <> '[' AND RIGHT(@IndexName, 1) <> ']') SET @IndexName = QUOTENAME(@IndexName);

--Handle the case where the left or right was quoted manually but not the opposite side

IF LEFT(@IndexName, 1) <> '[' SET @IndexName = '['+@IndexName;

IF RIGHT(@IndexName, 1) <> ']' SET @IndexName = @IndexName + ']';

-- Dig into the plan cache and find all plans using this index

;WITH XMLNAMESPACES

(DEFAULT 'http://schemas.microsoft.com/sqlserver/2004/07/showplan')

SELECT

stmt.value('(@StatementText)[1]', 'varchar(max)') AS SQL_Text,

obj.value('(@Database)[1]', 'varchar(128)') AS DatabaseName,

obj.value('(@Schema)[1]', 'varchar(128)') AS SchemaName,

obj.value('(@Table)[1]', 'varchar(128)') AS TableName,

obj.value('(@Index)[1]', 'varchar(128)') AS IndexName,

obj.value('(@IndexKind)[1]', 'varchar(128)') AS IndexKind,

cp.plan_handle,

query_plan

FROM sys.dm_exec_cached_plans AS cp

CROSS APPLY sys.dm_exec_query_plan(plan_handle) AS qp

CROSS APPLY query_plan.nodes('/ShowPlanXML/BatchSequence/Batch/Statements/StmtSimple') AS batch(stmt)

CROSS APPLY stmt.nodes('.//IndexScan/Object[@Index=sql:variable("@IndexName")]') AS idx(obj)

OPTION(MAXDOP 1, RECOMPILE);