SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bcacbe70a5ab8fbe018812fa1d2f1385081decbbbc46a5120c38c63eab80a939' 
  AND token = 'AKcvhTrMdoUEiHCrfQ6SrF9kcfGOlNvh7jVJs1HVNBY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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