SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cc6d6a109a16e5f09be0ef708f703a1cbfb5c2b50502a883d3bc05e1a443a1d3' 
  AND token = '4u6gplI/DboEmXaIooM8lZzWDLCewPTnjm7mODUeDQk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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