SELECT 
  * 
FROM 
  cscart_vd_vendors_relationships 
WHERE 
  brand_id = 220

Query time 0.00038

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_vd_vendors_relationships",
          "access_type": "ref",
          "possible_keys": ["brand_id"],
          "key": "brand_id",
          "key_length": "4",
          "used_key_parts": ["brand_id"],
          "ref": ["const"],
          "rows": 15,
          "filtered": 100
        }
      }
    ]
  }
}

Result

id brand_id feature_id variant_id lang_code
3781 220 653 2128 es
3783 220 649 1925 es
3784 220 649 1926 es
3785 220 649 1927 es
3786 220 652 2125 es
3787 220 652 2123 es
3788 220 652 2106 es
3789 220 652 2124 es
3790 220 652 2110 es
3791 220 654 2137 es
3792 220 654 2140 es
3793 220 654 2141 es
3794 220 654 2142 es
3795 220 647 1889 es
5921 220 661 2198 es