[{customer_id:"23424",customer_23424_value:5000}]

db.collection.find({$expr:{$eq:[{$let:{vars:{root:{$filter:{input:{$objectToArray:"$$ROOT"},cond:{$eq:["$$this.k",{$concat:["customer_","$customer_id","_value"]}]}}}},in:{$first:"$$root.v"}}},5000]}})