SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6848659bff02d873f5f10a14969d09f96880e325309582ebc65d99717add301' 
  AND token = 'LefHx8nLH1Yg+7MIQaPoA2GOwhiblBSNA15n0watTVA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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