SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd38053c4cb4a9b6a235b96ed0679ce7acf261614d03984c879158a6608a6667' 
  AND token = 'yoiYyPJNQ4c+HiMddciDWxxS0aKyrFYuoD0Uz4OVcPA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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