SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f6feee7792f60f25fd27ea083bb553cc4fa52d55989d7754e5416d735b51c5c' 
  AND token = 'pEdFBus0sN7IHzAWa+mKZKWuaZZHaqlyU3nhAJXYl0U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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