SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0f90d3d79f08db45d3f624a0411293978d400cd52ce4105406fdaeed46b52103' 
  AND token = 'vJ50befAO3jZSv4OFFONlEtWADZduUy75kxMFQbRwY0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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