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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd21f4cc0ca363b3a09739dffcb4793703dd0f1385e2936b1f8fb9ec29c8b4d86' 
  AND token = 'oIGXLOdXwG78wI2i3wjGHkvdxvKwel8RXQkHdMU74GU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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