SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9976e9f731846e30c75a796021570e99869889cfa72df6c6eb835c6210dc4d05' 
  AND token = 'mCq1MGoC/pKO6OPVZEqyUZZmBhMFMdkw/SNjlhvdITg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}