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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0976efb33d02643707ef453513634d79200bb704f4a6e7a4a8e01e6a053c0cd' 
  AND token = '8FgJkUeo6sQFAHhcqwDnvxGyV/p3WMnx52SNtfpu2Nk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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