SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f91858faa0408ecfcc5526780d2e8f8c06ddb726af4de5527d294c3fdf284130' 
  AND token = 'fwGyQvz8C7pTGgWtF+2VWerQ++WIk3/8kGuBqmUiBuo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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