SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6539206b6d462f24afd58c6280cc35804dcde2765681f27aca05b64d7f075056' 
  AND token = 'VrFKVD8MhaeTyDTcxNJoLdE+AO4XFkFNHgKCHcLfJy0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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