SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '307a0a6498a82abc39dfe94d7b45748f7ccb6e898e71e80f57d5e2f11b880a67' 
  AND token = 'JupjZEwKJdYRzFhGP4W+aUOYzseZCQ+jTLuPqZf1FAo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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