SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91f34ef4c6304258064449e514c69bf0aa99a7468fb452d5dbf0e5d458dcbeb2' 
  AND token = '/2IUDZkakqinvbVLeVhLRly1U6AMWCQUE7sbPfk1QsY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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