SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd562974033a8567748b9072e6edba3f56682c9737c4ddd634df7adb7952156fa' 
  AND token = 'qMBmZu4qfF0NavYAoVXvBasBIXIj+p7IYIHItgdBDjs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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