SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1ac1e88c0108016d6df77dd303d8fbe188625d34707faabda1f3e454cd916406' 
  AND token = 'qUELpnjXYNoPimJ61vMIGRSA+24YIvAqFJtPooqUBOc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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