SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0fad8298414dae9ce9e3943371c9857552bf26933af4da7b231fd54fbd0d4a1c' 
  AND token = 'zMC3dUsH7ENIOYequW0XLWKFfwqis4qhGVMhCwmvquY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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