SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'bdb06ad4e029c310603b400955fdf78349ed4a52f872a946a9f8b72e4223c89c' 
  AND token = 'leG8tnOgKRlaLTzNlzWbgulEQIE4jIQl7Kf0feojohA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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