SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de050f67856d856d8720796f7d4b1f191b41a1f9f0d497c92e5e84a5438904d6' 
  AND token = '9V7fyUc3+/zPJGZ3JYcrAFhBnrm25ZZxkMLDZihR8tQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}