SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35715db08c491cabb37ad384cacb516c34d8313068335c5387c629fd12d65f42' 
  AND token = '7cfjDnKfs6vA0zFHQ42XOkRKm69v3DA60TxoC9iwXOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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