SELECT 
  wishlist_id 
FROM 
  cscart_ec_hb_vendor_favts 
WHERE 
  user_id = 0 
  AND FIND_IN_SET(7, blog_ids)

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "2.41"
    },
    "table": {
      "table_name": "cscart_ec_hb_vendor_favts",
      "access_type": "ALL",
      "rows_examined_per_scan": 2,
      "rows_produced_per_join": 1,
      "filtered": "50.00",
      "cost_info": {
        "read_cost": "2.21",
        "eval_cost": "0.20",
        "prefix_cost": "2.41",
        "data_read_per_join": "40"
      },
      "used_columns": [
        "wishlist_id",
        "user_id",
        "blog_ids"
      ],
      "attached_condition": "((`atulecarter_atul_demo1`.`cscart_ec_hb_vendor_favts`.`user_id` = 0) and find_in_set(7,`atulecarter_atul_demo1`.`cscart_ec_hb_vendor_favts`.`blog_ids`))"
    }
  }
}