SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8788fb2208d2eee4cb82103a48a69bbc53fcdc39d917abfa7f538c6f6e08804' 
  AND token = 'xROUgCiGOfMkUpkNOccAmnLG4UiOl7K+hdc0nRwRtnA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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