SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7351a6fe327da80b35194f174cbe1758491b0c6bf2982a8855adfa60022b1326' 
  AND token = 'teblsKd+79W61VjRISWnckfNYfkiylGfN3KLFFxwoOk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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