SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92f211e19696de9629eaa79d48edc8219bcf5d933b6c31eff4be4e5b87618855' 
  AND token = 'v1kQPVvunUP3i24NO4Ljp9HLBCbarsw3SZ1A8rIoDM0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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