SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49426d3b70d235a176035d52e8bbb44c8e52dc0f984ba487c75e84ce9086c7c5' 
  AND token = 'Vn6tXMyFToKOZ+XMlKM9zQLI34gU7EsjOqsdqk/Ior8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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