SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92a719861964a3cc84bf1a885cf5bbaabc33284a82df0def8ddf828f1f340508' 
  AND token = 'ry/XUEMt0UsSTWkxAgiuVCfAG75AC/AqFyyZ9d1hNL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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