SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '539a8c021fd048102024010e0dc74908fc93778ac6d00c6c58088730dd5958d9' 
  AND token = 'HSqLfjyvnl63vLLms2+tYbExwE1Tbm76TarLhWkXM2E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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