SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '706ea9ee6c434122efa18f7009e36f680a0ed60f8048580f36bf802f0b3c8653' 
  AND token = '1phwHmHWk7ucZ4BW/7VzjtPEHDcqdHlmku2dsP0suOo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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