SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a17583aab2df809e0c608d5ff0a678499bd62dd1f0aeef0f3331afc0409edf37' 
  AND token = 'REnIcJMJfe5pehT3MxUZ3jDYQqJnoRVAYi7CeTJOEkM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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