SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5571ae8c3b144276123a8d39c7beefa2b18f2f9edb8d89b0ee01844473c80b0a' 
  AND token = 'qTYd56+OVYZcjl9mGy/Gv6RUaDtYDYe93qBAj2j0Ztg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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