SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e9e86f287362661f342040ae63d91c780737d8f68b8b4edae691f48bce16c7bc' 
  AND token = 'xj+8/jm+GcHKMkousZ+t1ahgKypOYaRlK1CmW9LHDZA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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