SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe96c5f8c7d403920241850e88cc449f1c93af153a15e9b0c4c91f8e84b21906' 
  AND token = 'wAGcRjb7ZOCLxu3v62FKIlBoTIgeezqMlmNjXWEjrKs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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