SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '756939e296616e85bca5538d6bc70c664c28c44077aa52a8bac8716ec9b710a3' 
  AND token = 'DB1IsH5QMfEooq/+GQMaxoenz1LsL7DNBYL2zVMxcEM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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