SELECT 
  pfv.variant_id, 
  pfv.position, 
  pfvd.variant 
FROM 
  cscart_product_feature_variants AS pfv 
  INNER JOIN cscart_product_feature_variant_descriptions AS pfvd ON pfv.variant_id = pfvd.variant_id 
  AND pfvd.lang_code = 'en' 
WHERE 
  pfv.variant_id IN (
    1659, 2083, 2325, 1727, 1912, 2364, 1705, 
    1660, 1748, 2092, 2084, 2086, 2085, 
    2088, 2087, 2327, 1803, 2169, 2016, 
    1941, 1905, 1787, 2097, 2026, 1904, 
    2096, 2106, 1900, 2105, 1988, 2025, 
    1899, 1789, 2294, 1930, 2170, 1959, 
    1984, 1942, 2268, 1998, 1946, 1937, 
    1995, 2283, 2284, 2285, 2286, 2293
  )

Query time 0.00102

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "51.46"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "pfv",
          "access_type": "range",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id"
          ],
          "key_length": "3",
          "rows_examined_per_scan": 49,
          "rows_produced_per_join": 49,
          "filtered": "100.00",
          "index_condition": "(`gaseus`.`pfv`.`variant_id` in (1659,2083,2325,1727,1912,2364,1705,1660,1748,2092,2084,2086,2085,2088,2087,2327,1803,2169,2016,1941,1905,1787,2097,2026,1904,2096,2106,1900,2105,1988,2025,1899,1789,2294,1930,2170,1959,1984,1942,2268,1998,1946,1937,1995,2283,2284,2285,2286,2293))",
          "cost_info": {
            "read_cost": "29.41",
            "eval_cost": "4.90",
            "prefix_cost": "34.31",
            "data_read_per_join": "55K"
          },
          "used_columns": [
            "variant_id",
            "position"
          ]
        }
      },
      {
        "table": {
          "table_name": "pfvd",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id",
            "lang_code"
          ],
          "key_length": "9",
          "ref": [
            "gaseus.pfv.variant_id",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 49,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "12.25",
            "eval_cost": "4.90",
            "prefix_cost": "51.46",
            "data_read_per_join": "152K"
          },
          "used_columns": [
            "variant_id",
            "variant",
            "lang_code"
          ]
        }
      }
    ]
  }
}