SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6fb2cb64c41a62217781e98e1d702437304ff95e77767389335590163c9f947' 
  AND token = 'YTykXzn8Aiao+1DhEbjjnkK8eR/Ut4Scq/zS661jP9w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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