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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b581a3326b246a81c14fa6df7000525a76ba8f09c6f21e5471d7b0b2a50251d' 
  AND token = 'h0wVxF3vXzZrL1oMEUwjwrY4DxIK4dqTn0KtZO0mM/4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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