SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9d48a950d76ba8d0afa8c08a838a1bc9b696a76efc80b59c453940c7269e18b7' 
  AND token = 'cJfkwNKPQthLT70XXVV7j5AcURG5dadqaOGm8clrt7o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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