SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e9f6f9cdc38fe1fe55afbf1174c0df42eb3e456ef7ac6adfea80db7722df95c' 
  AND token = 'nUEb/ya3qgSMA5eleRAv08YL6RMcht2kxTiPsumi6fc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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