SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27434fe48861a3c86bb238da3a57309e6dbd9f2ea7dc8565a52cbb7d23448810' 
  AND token = 'MtnZBm5/Gm2S1k4n4N3rwivvolQPRIB/Egstdmj6Iio=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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