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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2dc76a06e8fef77a98876c9eefd74aa019835b93e0862ee3d7b626b9c19fdbd9' 
  AND token = 'WJFCUaYcqMqGryl+feWuTY0GDc7qJHlMjo9BhHuwWRE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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