SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '992d8df8ac1ac430dda6a603c6fc31d15fd985ec74829476d1c2a9935a769615' 
  AND token = 'jNzt6aSET9PESIVRGdy5xHolZMqijRKpoKfZEL4tISU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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