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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd7f8a333932337507696165c37f1b947810a776636ba5eb7a1f83083481c4ee2' 
  AND token = 'M3usjNdk6/dIJ8c2YODR7qbgiAYVLEw+FjlnYElTEH4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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