SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a1a48a12809e15235d80724bacbf9b23395919b815c3c9f366c6e39f7ab709a' 
  AND token = '1qUwHbgm/ekUgGDXCOTvrTxJJuIQY73qkXaFKiwp7CQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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