SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c5da43b334588b5dac48d181fcf2e7fde084d818e47a7a7a6e48e18cf0482e5' 
  AND token = 'lsmVTE1W3bMxAO3BpUHbDSokQZBtw9rM5GcZABGciXA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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