SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f4a3f2ba62902916bf5d6416fde382d478740f1752f28983c89a9a977845356' 
  AND token = '9pCtZbPjyrAqre3lYGGSfBjCqCyzPkK/uV5m5tEsjGg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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