SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'e4a92aca65685bc520f3db1252c568621650f009acd6843f69e65a3cbf519c14' 
  AND token = '2pUMKqjzxDJnjG3SHORqSu+B7VfA0hjagmUcsNeTBg8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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