SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6ae2280e2ca8266a5973091ffe3bbcf3a3a724adc948f53c6d47cfa9217dc6d' 
  AND token = 'sIKCYkSsW/uuGzxKZzPx+dJiLh0plqin9kD6EzWxrAE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

JSON explain

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