SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6e79b5ccc350eee085edd5a286296cbf165a4dd6a24628bd921ed48d47cea1f' 
  AND token = 'XTrJPX0ji0h2bsRZkvzPJV+sz63BwHuAbcuahLSrWpo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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