SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a861a2d884c7ad0db3152a272475e3423abb945e1bee1d8afd741114c14b3110' 
  AND token = 'uOlQUi3rQ1s68GPWOKjk8IUJfDlT0cMlO3MDzUwoRUE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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