SELECT 
  * 
FROM 
  cscart_vd_vendors_relationships 
WHERE 
  brand_id = 223

Query time 0.00037

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": 18,
          "filtered": 100
        }
      }
    ]
  }
}

Result

id brand_id feature_id variant_id lang_code
14637 223 661 2198 es
14636 223 649 1925 es
14635 223 648 1913 es
14634 223 654 2141 es
14633 223 654 2140 es
14632 223 654 2137 es
14631 223 654 2136 es
14630 223 647 1889 es
14629 223 662 2212 es
14628 223 662 2205 es
14627 223 660 2188 es
14626 223 658 2186 es
14625 223 652 2107 es
14624 223 652 2109 es
14623 223 652 2114 es
14622 223 646 1887 es
14621 223 653 2128 es