SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3b95a459cabcc1b288d2e3d7128e40881d5283237065e098b6014e7b9de3a25' 
  AND token = '6YO6WoEeR7I7qzKuGpCnTgYcdBt+jgMaTV9R0LQ0EQQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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