SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8bde5a6dd67a281fb102d666fe1cd80e7070aa50b65651d1cbe0cdce73502796' 
  AND token = '4Uxuj20LFksOvuvB8PWpYT6OCkAenK1qAmtOgFhilas=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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