SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '17a829fbd7a56bd581a903435f13c52453d00043494584f9b125c7a68e4433ac' 
  AND token = 'mJD7/SZwtx+IHWBEqetrAABloIv//XaEs1hgpBK5nw0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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