SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '89f97e09deb7a0026e513baf82c53885bca1ec9cd97676d81899a81c3e461896' 
  AND token = 'l4VE4egcUctS3WB55XdO+LBCt4MQDOZh3PVTl9spwuA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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