SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c75df412f6c1a590f5aab8202e7c80d9acb439c3e99ecb9c5cde767297a003f3' 
  AND token = 'V6Gsyk0XbBNPB4782KEYknqyq7Z/LVQvVlLRJzrvSMY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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