SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a79b6aeb4bde8ab36e414def8cc51029fd59dbde911c5b35176d265f63e57769' 
  AND token = 'mKHZ7BIY3gLaDBrGdlyFQ9YnWq4Tmk1FIvdKwOsqRPY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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