SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9462b8f767af03a5562a75baf8256687df26f0f7bf1a098c311191e01bd0e730' 
  AND token = '5MKOZHZSlBs1ZF8qnwjeXQthcXyM33WAY0vGdKwynCY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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