SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '830f0fa3e496bca03adaff09a5dd006897019e417d890c9d83426e9498b1006f' 
  AND token = 'g5Y8XLMMsOu1bh2XDDzKlEd8thfEWOULLvRDkxuc4Lg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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