SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2a426103757a25ce23b2ab438dcd34be93c4bde9f23225512837a43efff87ed' 
  AND token = '1nhRbCJrHnmj/esFteDBPKK2DTok2zrC7kv5LvQRek0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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