SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52ff1ab140a0dd77d158a19155b05c341d423ff744d09a7ab59b778090eeba9c' 
  AND token = 'W54p6RX91uyfeHy0B6E4g+xoYnludLbbfFkD0v8GV8g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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