SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '157bad9c43e183fa12e447a8470d40fb3a5d4649f06dfc113ede26094439c3b4' 
  AND token = '1yNj2f0jTsOk2EwXCSMlu7QO6VEkfNCI8Dr/qAHCNvk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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