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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '138de19dd3bd9731e22204933e90fe8ae8c4c504fb672e07bee9103ab47c9a69' 
  AND token = '0wyMnJk7s5qZV3Rk0dWW/d7tYZC8ckx1GBQznr6jgYM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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