SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '30898f14611e7c7b0067161ead923a9cda91e4f4bc79ea53a8105797b656b353' 
  AND token = '4z/ONGjpQ88hl9PL/MY0v+F6vA7ESGZVyDHe4mjEhnw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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