SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6df4eed5e2d8878c11582562bb524b04d3e1d4d2916c5a622aacaa4625b5adf8' 
  AND token = 'ltmF0+/cIdkr87mS+28xNc819XS0FUxkPPbVKBMSpfc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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