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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b76d0a3a9d8ce2c291cd78fcf1e2068ccd8faabe45431ce317f7cb60ed44aca' 
  AND token = 'hv7guqZgz1qOzqJUvxG3e3MD7uQ0XtALZR/XgoNhFZA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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