SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71bcc5621a0d5e3537ba0bb16d4ca15e770e27602a31b23efe6f071e33eacc93' 
  AND token = 'VTqfbUrINv+DqTnWxmbHpjdzkBxNhCAW555h5YKMEys=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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