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 (
    71100, 71099, 71098, 71097, 71096, 71095, 
    71094, 71101, 71108, 71107, 71106, 
    71105, 71104, 71103, 71102, 71109, 
    71116, 71115, 71114, 71113, 71112, 
    71111, 71110, 71117, 71140, 71139, 
    71138, 71137, 71136, 71135, 71134, 
    71141, 71164, 71163, 71162, 71161, 
    71160, 71159, 71158, 71165, 71172, 
    71171, 71170, 71169, 71168, 71167, 
    71166, 71173, 74807, 74808, 75637, 
    75635, 75636, 76709, 76708, 76707, 
    76710, 81692, 81693, 81694, 86164, 
    86163, 87193, 86266, 86297, 86298, 
    86299
  )

Query time 0.01644

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "pfv",
          "access_type": "range",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["variant_id"],
          "rows": 67,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (71100,71099,71098,71097,71096,71095,71094,71101,71108,71107,71106,71105,71104,71103,71102,71109,71116,71115,71114,71113,71112,71111,71110,71117,71140,71139,71138,71137,71136,71135,71134,71141,71164,71163,71162,71161,71160,71159,71158,71165,71172,71171,71170,71169,71168,71167,71166,71173,74807,74808,75637,75635,75636,76709,76708,76707,76710,81692,81693,81694,86164,86163,87193,86266,86297,86298,86299)"
        }
      },
      {
        "table": {
          "table_name": "pfvd",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "9",
          "used_key_parts": ["variant_id", "lang_code"],
          "ref": ["dev_db.pfv.variant_id", "const"],
          "rows": 1,
          "filtered": 100,
          "index_condition": "pfvd.lang_code = 'en'"
        }
      }
    ]
  }
}