SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f6066a0bf7ce627e6905e866078189e13239caf77b04f8885fd10d4a0dadde6' 
  AND token = 'MDcznxS4Dx0JvGCTIFI789AGZaeIqHBAs1lOTn5OSkU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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