SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '749720081101f320ab2f57a3293abb433ff372419d56dfb79826c42202620d99' 
  AND token = '5GSTVDlKP2kdj+z40BYGiScX3HUXB8uZDYdFuiZWb98=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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