SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a035f99871fe49b5c900a10efa4154bbf3be1372c042f6607c2bd8d8bc506b9f' 
  AND token = 'uIiMvUN1qsegAijGgmJWteC9jXWissm+sPRrhwrjqEY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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