SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b157f8b0cbd9fa76390ce787af270ec8d65f9a98af0cf091de84d4bc9da60577' 
  AND token = 'q83NwbLFJI/VbZCJxSoL6dCZSQBNgRHZ6nAzQWZeznM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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