SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16fe983ee789f8fc81482de446dfca6ab038213b279ba782f3d2433783c00e90' 
  AND token = 'WzmHEBBIzYoAiGfnicge4h30JFyPRJDz0SNNhredr4M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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