SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fad272bf16d8fd7554a33df351aa707a67332c2b49b49cf821faa184483c313' 
  AND token = 'L5IqTKgnPBH51HiDvRxOCyVrL053fobcBiOccaWVEO8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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