SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b9db1e6e3cd7644bbebb5f484f60cbaea1de8009ff2f7155780df0d1e4dac8e' 
  AND token = '4nMEhT5kU89jUzd/Qly9E9W5t4kx54HlZugS/3gQR4g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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