SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '54b0d141a7cb3060c30b16cb76a85c719c9aa9e6dbea082b4bdb5503080a1ed8' 
  AND token = 'tMrHsggUZKxR6tPD8Py/MM5tmrYb0TXXh1jmsma3SP4=' 
  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"
    }
  }
}