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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a176a1428ee5a406e6661237391d52c8d9215bd3fe669b4e193e8d8b1ffbae56' 
  AND token = '0RQ0pDCjlb+aR+zvPg2Tn9oVwQAlUxWCgebyZB4gccs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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