SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2f99f226fab4dbc62fb68bb79aaef43b772b1213431bcb018542c8b353e7de1' 
  AND token = '5VP/Zj9P9z5VSvo14zgWvcxCYq3bsBh3ato/+9Y3ZZg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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