SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e21cc8b41028db2d49d7868d0ebcd2f96f6a4d490b8eefcc265e30f4533a512' 
  AND token = 'cebq47iCJ/WcB1oczFOfRU+943GpmInabT+T+aYXYoI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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