SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21617b7f440dc27acb575c4aa5801f7bce45f7ed0cff2582d58953520cb9f158' 
  AND token = 'SxyuSzkSDnxyjS6zISUUq3ltqK4USTAf7CRmlpRbaEI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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