SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0ad73ab2589fba248ce25412282faa6d14321b64843ad468cb6c62737c72b86c' 
  AND token = '8qRmS9Urgxra/BRTNHBB3gMgC0fQhOsoRyFji+CmH4w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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