SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76f3769b169d2a94cc94d01d406ecf98d08162303ee571980b9151ad4bb0af36' 
  AND token = 'Fio/mmBl5tJd6RTCMZUC4dm7aT4puqWAmilWuCsD0jc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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