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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9b726a745c993f8a2cb45a74d348a3610d3d8fe7508b46a85622358db292b30f' 
  AND token = 'trOFH8VMq17d91amEb6pllWvd9C0QZTLeZKM//SkG7M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}