SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad0a77ca345bdd87488e7a9df6631b0dc69641723215086eae76991037c8eb04' 
  AND token = 'UWCV10BhRnmMKape+lgMj7DhpcGjiwuIwJheTmfUIZc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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