SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b75f4454f52b83a2a514712a3db78c75ae0097c93e7f8fc6b893735eb4ef3d48' 
  AND token = 'UWuOEhieogd2Ew9L57tKRcgaCylgaGz4XpslP24N0tQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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