SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6feeebb619ea0be694e3cc06fbecd877b702e66e061081d27f2fea7105f609a6' 
  AND token = 'Ok3pnjh2dioPWRpadyx/p9+XA9Z51sxx8gC3kvE/xqc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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