SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '393f94fe132063e7d965fc298026658ec10177983d394dd4dee524839380076d' 
  AND token = 'f5aGcEifZ0YTnVqMKHUvmQAArQs6wqxSkMDxYH9T7aw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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