SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d568012d243656b8c93f169954aa6e1f38c01698bb199b9e87372f9a0594d41' 
  AND token = 'BMY9EgczOTaTVJen5uVE+hCRqDCbJ92QHj0QdtZm0V4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}