SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2278289996575ab6a9919ffce6e6340bf625bc7b7e194ca3326f70475c5b2138' 
  AND token = 'Dp4pjzhsj0pv+mFQndiddkx9qgYwMjodhlrcHotNJdY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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