SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31ffb5a9289b09591468434495f6cfee3e35117a6592d5246d1e1d1860dc7933' 
  AND token = 'qppnmtzxFZiOEzy35p1B+K4eRpMB7q7FXpCHEUotvGU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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