SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b9ba5af5cef616b752846fb9d324c531672e5939f670c3ec61f581da45214a1' 
  AND token = 'ULZxQBk0Kj9RGxMfYO2KoZBn/HrSPVMAZzampgaxQh4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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