SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '44714b236c256c1beb5ba2f89c733d44e51642de3b5a7ee333fbdc6cf2ee4334' 
  AND token = 'Zni/F6tot6Gsfu83kwQnEBrvbadmdmbpM8lsUJVlTqk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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