SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cbd21c71202c744dcd44e8fa23d571ec7521d74108c636df46fe979706103549' 
  AND token = 'PgjqAGRdActjiNMN/bH3ha0QNn0XobYr4tNrhuRGkyY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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