SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d98525d45a3ed79945b207e016576884260395a7ab683cc32ea34bce8af7a43' 
  AND token = 'bTORA4cOAf4xwViXR7dNlvaDQEEFZLleUnCwjpL9RMM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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