SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b5101092750635ac387b4108206f71a2a1259520826bfac6a202ad3bb1efa6a' 
  AND token = 'Tvf2CazdBmgn7RyKymOF8gw3swHdK5WS9i4P53Z/W5k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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