SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53355bd5fcc119938ccacfe28f242ec90acf4914c0988c8a92ce9d5b5dc8101a' 
  AND token = 'L+VlRf5NSARbiwmpL1bM7LCDg+NPRiJ1PWHU42JMTvk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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