SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a413497a2b9fe4ca0fe1305ef720dca44a76c1353e6da563b0fd1d8b064997f6' 
  AND token = 'ss6vU5fQNQzGu0kHYYkTcVeOrZUpL/mGqu7kTgPBxt8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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