Fix too many SQL variables issue in updateMaturedBalance

[chris124567]

Fix this error encountered in block 345995:

ERROR   explorer        failed to sync store    {"error": "failed to process updates: failed to update chain state: failed to apply chain update \"345995::c2896f8e\": ApplyIndex: failed to update matured balances: updateMaturedBalances: failed to query address_balance: too many SQL variables"}