SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a39c9de630ac528379284667de1df1ad3b8b95696c041bad1f1f796afc3e68f' 
  AND token = 'IElGSdqRxKgWOxILZLoyOq+sxM8JCZJV6SBVOVujXkU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}