An index {status:1, qty:1} exists. This query returns totalDocsExamined: 5 in explain even though every needed field is in the index. What single change makes it a covered query (totalDocsExamined: 0)?
db.items.createIndex({ status: 1, qty: 1 })
db.items.find(
{ status: "A" },
{ status: 1, qty: 1 }
)