SELECT 
  * 
FROM 
  cscart_vd_vendors_relationships 
WHERE 
  brand_id = 60

Query time 0.00032

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": 19,
          "filtered": 100
        }
      }
    ]
  }
}

Result

id brand_id feature_id variant_id lang_code
15973 60 661 2198 es
15972 60 649 1925 es
15971 60 648 1905 es
15970 60 654 2142 es
15969 60 654 2141 es
15968 60 654 2140 es
15967 60 654 2137 es
15966 60 647 1889 es
15965 60 662 2213 es
15964 60 662 2212 es
15963 60 662 2205 es
15962 60 662 2202 es
15961 60 660 2187 es
15960 60 658 2177 es
15959 60 652 2104 es
15958 60 652 2110 es
15957 60 652 2103 es
15956 60 652 2116 es
15955 60 646 1887 es
15954 60 653 2132 es
15953 60 653 2129 es