SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b644927b44860226eefb8802393b52c6ac60857f08a9866283e15e8a27ea821' 
  AND token = 'JpYdmbkS7W0feoKvYSZB8CEr2NGS4H64pXIBwHlWaYE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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