SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81df65a6c6600d0bbdb7a441b723b91331f669815192d6fff3757022d4987d86' 
  AND token = 'JHBCfEfCmpsL6f8rGd/1nem1D2BrlhF1koeTXlD1e3U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}