SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '33cd7999d91ac16e8c79cc282ce5957bf308a083758118c125680f1be46af516' 
  AND token = 'e2LmZN6dxuS4NzP/r+FldQ4KrZL1ghBDhnV+i0LytzU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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