SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d9c1e3a2a816d415e2394d442558b8dac8a170ae57ad69949ed75ddaee1c4ac' 
  AND token = 'o0/RQnxFRg/HCWvxt2Z6hNNCiFGsVzbhOxu5PAYAXJo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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