SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dce9381b9b28cdffbbfff944a1690f77fafd1689b3a468ecb9b9f514811a339e' 
  AND token = 'qC3hGBaUXdIoEOHvz/ok9zwCsIMCeHp5UgFwTbT96Pc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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