SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dff8d8ec66e000d2dedaf30ce915f7b0ec294da820a60e5fd74f4823fdb2ce06' 
  AND token = 'fLXngIlUpDdgyGJ0rYJLtlbmF0OYJLjotVFYyJusfxE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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