SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fecfa88d2ffd6a8d1e9fe5748152f7591b06035a67d4edbafdc9e39ebb240b90' 
  AND token = 'iwDlvYyKZJlmR2kBUv9v2bUF0uiTxOG4h2Ww6Hh34zI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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