SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38e838871c540ddbeb2fddef4cff49d03e2f992037f1e152a278bef2699152b6' 
  AND token = 'jxyc56L3kcHiB6cmhOzQ7zIPKfjsCm6zHLJpMd4Qb0U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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