SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '771a0eb67778dcde51cf8b941af582a146acc24617de5891dc034a11cc1aa108' 
  AND token = 'PsDSbIMtbHOHYnoiJRMlZmt61+HZdbeASryxWkXbC1g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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