SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28e2b2922b09a6f95dbc71c68e5e02d0a01b7f369edf5c56b38bfffb70525781' 
  AND token = '8jFN+IdtmyZZvqi2aTwhNyMJxn4vXlxc+DgZui8N2f4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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