SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5a60f8fccda74f9d2885695681dff07adb5f11126f9da33750acd00618c40ec' 
  AND token = 'gWXKhqn1ZcKpUDPA7TgFOk+F+EByM+xvGV3Jn5WdARo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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