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 (
    2347, 2345, 2348, 1659, 2080, 2327, 1706, 
    1912, 2122, 1803, 1712, 1789, 2087, 
    1973, 2092, 2026, 1904, 2095, 2280, 
    1941, 1905, 2350, 2027, 2145, 1705, 
    1660, 2086, 1974, 1980, 1972, 2094, 
    1937, 1988, 2082, 2291, 1899, 2089, 
    1787, 2090, 2016, 1900, 2093, 1945, 
    1989, 2088, 2083, 2325, 2007, 1748, 
    2278, 2084, 2170, 2081, 1742, 2097, 
    2012, 2013, 2129, 1694, 2000, 2085, 
    1942, 2168, 1995, 2285, 2283, 2294, 
    2096, 2075, 2286, 1983, 1959, 1984, 
    2288, 1946, 2336, 1926, 1930, 2287, 
    2297, 1998, 2284, 2299, 2282, 2167, 
    2025, 2144, 2343, 2293, 2281, 1721, 
    2123, 2107, 1902
  )

Query time 0.00100

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "98.71"
    },
    "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": 94,
          "rows_produced_per_join": 94,
          "filtered": "100.00",
          "index_condition": "(`test2_gaseus`.`pfv`.`variant_id` in (2347,2345,2348,1659,2080,2327,1706,1912,2122,1803,1712,1789,2087,1973,2092,2026,1904,2095,2280,1941,1905,2350,2027,2145,1705,1660,2086,1974,1980,1972,2094,1937,1988,2082,2291,1899,2089,1787,2090,2016,1900,2093,1945,1989,2088,2083,2325,2007,1748,2278,2084,2170,2081,1742,2097,2012,2013,2129,1694,2000,2085,1942,2168,1995,2285,2283,2294,2096,2075,2286,1983,1959,1984,2288,1946,2336,1926,1930,2287,2297,1998,2284,2299,2282,2167,2025,2144,2343,2293,2281,1721,2123,2107,1902))",
          "cost_info": {
            "read_cost": "56.41",
            "eval_cost": "9.40",
            "prefix_cost": "65.81",
            "data_read_per_join": "107K"
          },
          "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": [
            "test2_gaseus.pfv.variant_id",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 94,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "23.50",
            "eval_cost": "9.40",
            "prefix_cost": "98.71",
            "data_read_per_join": "293K"
          },
          "used_columns": [
            "variant_id",
            "variant",
            "lang_code"
          ]
        }
      }
    ]
  }
}