SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '09dad057bb22061489e7cf596120d647bd1274173076aa09760e01146fea8c47' 
  AND token = 'mVei2bFz8P/YmHpDXwpBn5AF8xRzJUyJWs9scAdNkKg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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