SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb5e6848638f18c2cdd9abae75b9ecd0a4f2f5770832cebb21e274111a063b44' 
  AND token = 't4xSYaUiuvWq6ydm8XGXdQ/yzFMSykUQDm5qOE7yYLg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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