SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d662132a02eb3264f39f99085d686622ac02ccf825f12445e92d3a199308dc0' 
  AND token = '5CWzYpDq+HjMQgpZoal8ct3k5OLMHvgIUeFdkPe2nAg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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