SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb587cad1333dc8270d57ec3ebf160c326995c19129cc1f038068026fc513ad2' 
  AND token = 'H2PhUECxSj3qdiSNY23w3rtThv07kvAnXacB3zGjszU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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