SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '482b948e66cdf937a23d8d5f1edda6161cef7e98120a35b9444361bfc46ea320' 
  AND token = 'ASQQAILXSv4deBMMwn1geXe7f72GbSTsGXviTbTnkdY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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