SELECT 
  object_id 
FROM 
  cscart_settings_objects 
  LEFT JOIN cscart_settings_sections ON cscart_settings_objects.section_id = cscart_settings_sections.section_id 
WHERE 
  cscart_settings_objects.name = 'sidebar_background_image' 
  AND cscart_settings_sections.name = 'vendor_panel_configurator'

Query time 0.00038

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_settings_objects",
      "access_type": "ref",
      "possible_keys": ["name", "section_id"],
      "key": "name",
      "key_length": "386",
      "used_key_parts": ["name"],
      "ref": ["const"],
      "rows": 1,
      "filtered": 100,
      "index_condition": "cscart_settings_objects.`name` = 'sidebar_background_image'"
    },
    "table": {
      "table_name": "cscart_settings_sections",
      "access_type": "eq_ref",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "4",
      "used_key_parts": ["section_id"],
      "ref": ["admin_test.cscart_settings_objects.section_id"],
      "rows": 1,
      "filtered": 100,
      "attached_condition": "cscart_settings_sections.`name` = 'vendor_panel_configurator'"
    }
  }
}