SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '238e90a43fc34ae87810b39f3ce37f6730667fb2e58c14360d51df967b4a1f50' 
  AND token = 'OYB9UzeCZxvnsCalBBIjtAk/oHE6KMJVzg/idgRbDgQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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