SELECT 
  sidebar_c_bg as 'bg', 
  sidebar_c_title as 'title', 
  sidebar_c_desc as 'desc', 
  sidebar_c_link as 'link', 
  sidebar_c_link_text as 'link_text' 
FROM 
  cscart_categories 
WHERE 
  category_id = 1866

Query time 0.00040

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_categories",
      "access_type": "const",
      "possible_keys": ["PRIMARY", "p_category_id"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["category_id"],
      "ref": ["const"],
      "rows": 1,
      "filtered": 100
    }
  }
}

Result